Download Electricity Lab NV6000 Operating Manual Ver 1.1 141

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Electricity Lab
NV6000
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Operating Manual
141-B, Electronic Complex,
Pardeshipura, Indore- 452 010 India
Tel.: 91-731- 4211500
email: [email protected]
Toll free : 1800-103-5050
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Ver 1.1
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Electricity Lab
NV6000
Table of Contents
1.
Introduction
4
2.
Features
5
3.
Training Kit-Includes
6
4.
Technical Specifications
7
5.
Experiments
Experiment 1
Study of the Resistances individually, as well as in series
and in parallel connections.
•
Experiment 2
Study of the ohm’s law mathematical relation ship between
three variables voltage (V), current (I) and resistance (R).
11
•
Experiment 3
Study of the voltage and current flowing into the circuit.
13
•
Experiment 4
Study of the behavior of current when light bulbs are
connected in series/parallel circuit.
16
•
Experiment 5
Study of the Kirchhoff’s Law for electrical circuits
17
•
Experiment 6
Study of the R-C circuit and find out the behavior of capacitor
in a R-C network and study the phase shift due to capacitor.
20
•
Experiment 7
Study of the L-C circuit and its oscillations.
23
•
Experiment 8
Study of the characteristics of a semiconductor diode.
25
•
Experiment 9
Study of the characteristics of a transistor.
28
•
Experiment 10
Understanding the Faraday’s Law of electromagnetic induction.
33
•
Experiment 11
Study of the behavior of current when inductance is
introduced in the circuit.
35
•
Experiment 12
Study of the Lenz’s Law and effect of eddy current.
36
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Experiment 13
Study of the relay and construct a switching circuit by using relay.
38
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Experiment 14
Study of the Oersted experiment.
40
•
Experiment 15
Study of the phenomenon of mutual induction.
41
•
Experiment 16
Construction and study of the step down transformer with the
help of given coils and cores.
43
•
Experiment 17
Construction and study of the step up transformer.
45
•
Experiment 18
Study of the effects of moving I core on a step up transformer.
46
•
Experiment 19
Conversion of a galvanometer into voltmeter.
47
•
Experiment 20
Conversion of a galvanometer into ammeter.
49
•
Experiment 21
Study of the Hysteresis curve.
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Warranty
7.
List of Accessories
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Introduction
The NV6000 Electricity Lab is a versatile Training kit, for a laboratory. It is
designed such that all the basic electrical circuits can be tested with the help of this
trainer kit. The experiments given with training system develop mental starting from
an introduction to the circuit, basic fundamentals and complete circuits like series and
parallel circuits, electromagnetic induction, coil behaviors with AC and DC circuits
diode and transistor characteristics etc. This simple training kit provides a strong
foundation for future studies in electrical or electronics. This takes students from the
basic of ohm’s law, through simple series and parallel circuit analysis and into same
elementary aspects of electronics where they will build circuits using capacitors,
transistor and diodes. Student can study how the resistance of a light bulb filament
changes as it heats up.
With this system a set of coils and cores are provided. These high quality coils and
laminated iron cores provides an effective introduction to electromagnetic theory.
Each coil is labeled with number of turns. These can be used in study of
Electromagnetism : It shows how the magnetic field can be increased by
increasing the current, by adding an iron core or by using coil with more turns.
2.
Induction : We can pass a magnet through a coil and detect the resulting
electromotive force with galvanometer. So it shows how the EMF depends on
number of turns in the coil and on the relative velocity of the magnet and coil.
3.
Transformers : We can mount coils on the U or E- shaped iron cores to
demonstrate mutual induction. Then connect a load to investigate power transfer
and basic transformers theory with an AC power supply. These are not ideal
transformers. As is true for any transformer using separate coils, the flux
linkage between coils is very less. The voltage transformation ratio are therefore
proportionately below the ideal values based on the number of turns per coil
within this limitation, effective quantitative investigations can be conducted
using these coils and cores set.
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Features
•
Stand alone operation
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Durable, Easy to use kit
•
Includes all the basic electrical fundamentals
•
Solder less connection
•
Complete set of coils and cores to understand the basics of electromagnetic
induction and transformers
•
Provided with a component box to perform all the experiments
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1.
Training Kit-Includes
Components box with
a.
Resistors
b. Capacitors
c.
Transistors
d. Diode
e.
Potentiometer
E, I, U cores
3.
Set of coils
4.
Magnetic compass
5.
Bar magnets
6.
Screw Driver
7.
Multimeter
8.
Connection patch cords
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2.
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Technical Specification
DC Power Supply
:
5V, 200mA
AC Power Supply
:
6V, 1A
Relay
:
5V
Galvanometer
:
30 – 0 – 30
Galvanometer Resistance
:
80-125 Ω
Light Bulbs
:
6V
Potentiometers
:
25Ω, 1 W
10 KΩ, 1W
Switch
:
1 Pole, 2 Way Toggle Type
Core Types
:
E, I, U
Coils
:
Wire
Dimension
(mm)
Maximum
Current
(Amp.)
Inductance
200
0.818
1.46
590µH
400
0.573
0.728
2.3mH
800
1600
3200
Mains Voltage
0.404
0.363
9.2mH
0.251
0.144
34.2mH
0.170
0.072
134mH
:
:
1 Amp.
220V AC ± 10%, 50Hz
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No. of Turns
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Experiment 1
Objective :
Study of the resistances individually, as well as in series and in parallel
connections.
Theory :
Resistors are identified or values can be known by their colour codes. There is a set of
co-axial rings or bands printed on the resister. In order to understand the significance
of these rings, we have to go through the following table.
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Figure 1
For example : If any unknown resistor has following colour bands.
1. Brown
2. Black
3. Black
100 x 100 ± 1% Ω
100 Ω ± 1%0
5. Brown
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So the value can be determined as
4. Black
Resistance in Series :
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The first three rings or strips from one end give the first three significant figures of
resistance in ohm. The fourth ring indicates the decimal multiplier. The last ring
indicates the tolerance in percent above the indicated values.
Resistance are said to be connected in series between two points, if they provide only
a signal path between the two points. When resistors are connected in series some
current flows through each resistor when some potential difference is applied across
the combination. It means that the equivalent resistance of any number of resistors is
equal to the sum of their individual resistances.
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RS = R1 + R2 + R3
Figure 2
Resistance in Parallel :
Resistance are said to connected in parallel if the potential difference across each of
them is the same and is equal to the applied potential difference.
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1/RP = 1/R1 + 1/R2 + 1/R3
Figure 3
For any number of resistors connected in parallel the reciprocal of the equivalent
resistance is equal to the sum of the reciprocals of their individual resistances.
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Procedure :
Take any three resistors of same value and enter the colour codes of resistors
into the table.
2.
Enter the value of resistors according to the colour code in the table.
3.
Enter the tolerances in the table.
4.
Now measure the resistance of all three resistors with the help of multimeter.
Enter the measured value in the table.
Resistor
1
3
5.
Coded
Tolerance
Resistance
Measured
Resistance
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Colours
1 2 nd 3 rd 4 th
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1.
Now connect the three resistors in series on the trainer board. Measure the
resistance of the combinations as shown in the following diagram by connecting
the leads of the multimeter between the points at the ends of shown arrows. You
can calculate the resistances by using formulas and can compare with the
multimeter readings.
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Figure 4
Calculate :
R12 = ……
R23 = ……
R123 = …..
It is clear that R123 = R1 + R2 + R3
6.
Now connect the resistors in parallel as shown in figure and measure the
resistance of different combinations.
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7.
8.
Figure 5
Calculate :
R12 = ……
R23 = ……
R123 = …..
It is clear that 1/R123 = 1/R1 + 1/R2 + 1/R3
Compare the result of formulas with the result of multimeter.
Now you can take different types of resistor values and repeat the above steps.
Construct a combination of series and parallel connections of resistors.
Figure 6
Calculate :
R1 = ……
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R23 = ……
R123 = …..
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Experiment 2
Objective :
Study of the ohm’s law mathematical relationship between three variables
voltage (V), current (I) and resistance (R).
Theory :
We know that electric current is proportional to drift velocity which is turn in
proportional to electric field strength. The electric field strength is proportional to
potential difference. So the electric current is proportional to potential difference,
which is ohm’s law. If V is the potential difference and I is the current, then V = IR
where R = resistance
Since current I is proportional to the potential difference V therefore the graph
between V and I is a straight line.
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V – I graph for an ohmic conductor
Figure 7
Procedure :
1.
Take any one resistor from given component box. You can detect its value from
last experiment and record it in table.
2.
Now connect the circuit as shown in figure 8.
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Figure 8
a.
Connect a resister’s one end to an ammeter and other end to –ve terminal of
DC power supply.
b. Connect positive of DC power supply to other end of ammeter.
3.
Switch ‘On’ the trainer board.
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4.
Set the multimeter to the appropriate range and measure the current flowing
through the resistance. Record this value of current in the table.
Note : when current is to be measure we have to connect ammeter (multimeter)
in series.
5.
Now disconnect the above setup and connect the new circuit as shown in figure
9.
a.
Figure 9
Connect a resister across the DC power supply.
b. Connect a voltmeter across the resistance.
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6.
Now measure the voltage across the resistor (Note that voltage is to be measure
in parallel).
7.
Record the corresponding voltages/current in table for different resistors. You
can start with the lower values of resistors.
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Resistance
(Ω)
Current
(A)
Voltage
(V)
Voltage/
Resistance
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Draw graph between current (vertical axis) and resistance (horizontal axis). It is
clear that current is inversely proportional to resistance.
9.
Now you can compare the values of V/R with current. According to the ohm’s
law current is given by ratio of voltage to the resistance.
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Experiment 3
Objective :
Study of the voltage and current flowing into the circuit.
Theory :
In any series circuit the voltage is distributed according to the size of the resistor. It
means that for high value of resistance a high voltage drop will be there and for a low
value resistance low voltage drop will be there.
In any parallel circuit the voltage is the same across all the elements of parallel
combination. It means parallel resistances represent a single resistance and that’s why
the same voltage drop is there. In combination of series and parallel circuits the
parallel resistors were actually one resistor, which is then in series with the first then
the rules are same as above.
In series circuit the current is same for all values of resistance. But in parallel circuit
current is not same in all the branches it will be different for different resistances. In
any resistance circuit series or parallel or both the voltage, current and resistance are
related by ohm’s law. i.e. V = IR This can be observed in results.
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Procedure :
Connect the three resistors of same value in the series circuit as shown in figure
10, connect the DC power supply across it.
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2.
Figure 10
Measure the voltage drop across the resistance and series combinations with the
help of multimeter.
V1 =
R2 =
V2 =
R3 =
V3 =
R12 =
V12 =
R23 =
V23 =
R123 =
V123 =
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R1 =
Repeat the steps with different values of resistors.
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3.
Connect the parallel circuit and measure the voltage across each of the resistor
and combination.
V1 =
R2 =
V2 =
R3 =
V3 =
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R1 =
R123 =
4.
Figure 11
V123 =
Connect the combination of series and parallel circuit.
V1 =
R23 =
V23 =
R123 =
V123 =
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R1 =
Figure 12
5.
Now repeat the above steps for different values of resistances.
6.
Again connect the same values of resistors in series, connect the DC power
supply across it.
7.
As we know that for current measurement we have to connect the ammeter in
series. So make connections according to figure 13.
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Figure 13
8.
Now measure the current from multimeter it is the current between supply and
1st resistance say I1.
9.
Now connect the multimeter as ammeter between R1 and R2 and then between
R2 and R3 and between supply and R3 for current measurement record the
current.
R1 =
I1 =
R2 =
I2 =
R3 =
I3 =
It is clear that’s in series current is same.
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10.
Connect the parallel circuit of resistances and measure the current of each
branch as shown in figure 14.
I1 =
R2 =
I2 =
R3 =
I3 =
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I0 =
Figure 14
It is clear that in parallel current is depends on the branch resistance. It is not
same for all branches of parallel circuit and it follows ohm’s law, for high value
of resistance low current is there and for low value of resistance high current is
flowing for a same input voltage.
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Experiment 4
Objective :
Study of the behavior of current when light bulbs are connected in series/parallel
circuit.
Procedure :
1.
Connect the circuit as shown in following figure 15.
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a.
Figure 15
Connect two light bulbs in parallel.
b. Connect third light bulb in series with parallel combination of two bulbs.
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Connect DC/AC power supply between one end of parallel bulbs and other
end of series bulb.
Now as you switch ‘On’ the trainer board the current flows in the circuit. It is
equally divided in the two parallel branches, but flows in full amount through
the series bulb.
3.
Result of this is, parallel bulbs are glowing with low intensity and series is
glowing with full light.
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Experiment 5
Objective :
Study of the Kirchhoff’s Law for electrical circuits.
Theory :
Kirchhoff’s laws are simply the expression of conservation of electric charge and of
energy. There are two famous rules developed by Gustav Robert Kirchhoff in the year
1842. After him these rules are known as Kirchhoff’s rules.
Kirchhoff First Law or Kirchhoff’s current law or junction rule :
In any electrical network the algebraic sum of currents meeting at a junction is always
zero.
ΣI=0
The currents directed towards the junction are taken as positive while those directed
towards away from the junction are taken as negative.
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I1 + I2 – I3 – I4 – I5 = 0
I1 + I2 = I3 – I4 – I5
Figure 16
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From above expression we can say that the sum of current flowing towards the
junction is equal to the sum of currents leaving the junction.
Kirchhoff’s Second Law or Kirchhoff’s voltage law or loop rule :
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The algebraic sum of all the potential drops around a closed loop is equal to the sum
of the voltage sources of that loop. This voltage law gives the relationship between
the ‘voltage drops’ around any closed loop in a circuit and the voltage sources in that
loop. The total of these two quantities is always equal. Equation can be given by
E source = E1 + E2 + E3 = I1R1 + I2 R2 + I3 R3
Σ E = Σ IR
i.e. Kirchhoff’s voltage law can be applied only to closed loop. A closed loop must
meet two conditions.
1.
It must have one or more voltage sources.
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2.
It must have a complete path for current flow from any point, around the loop
and back to that point.
Procedure :
1.
Connect the following circuit.
a.
Figure 17
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Connect R1 (330Ω) to +ve end of supply and its other end to one ends of R2
(220Ω) and R5 (100Ω).
b. Connect other end of R2 to one ends of R3 (200Ω) and R6 (100Ω)
c.
Now connect other end of R3 to one ends of R4 (100Ω) and R7 (100Ω)
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d. Connect other end of R4 to one end of R8 (100Ω)
e.
Connect other end of R8 to one end of R9 (100Ω)
f.
Connect other end of R9 to other ends of R7, R6, R5 and to one end of R10
(100Ω)
g.
Connect other end of R10 to –ve end of power supply.
Now for testing the KCL at node ‘B’ we have to measure the following.
3.
First remove supply connection to R1, now measure incoming current Iin
between +ve end of source and first end of resistor R1 i.e., connect the
multimeter as ammeter between these two points.
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Note : whenever we have to measure the current in the branch, we have to
connect the ammeter in series and after measuring the current disconnect the
ammeter and make the connection as previous.
4.
Measure outgoing current I1 between second end of R5 (when this terminal is
not connected to trainer) and common end of R10 and R9.
5.
Measure outgoing current I2 between second end of R2 (when this terminal is
not connected to trainer) and junction of R3 and R6.
6.
Check whether the incoming current Iin is equal to the sum of outgoing current
(I1 & I2).
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7.
Repeat the procedure for junction point C, D, G, H, I.
To test the KVL in the loop ABIJ measure the following :
Measure current Iin following through resistor of 330Ω with the help of
ammeter as step (3).
2.
Measure current I1 as step 4.
3.
Measure current Iout between point J and one end of resistor R10.
4.
Calculate the different IR drops in the ABIJ loop (sign of IR drops should be
given after considering direction of current.)
5.
Measure the sum of IR drop with their sign.
6.
Equate the sum of all IR drops (with their sign) and sum of the source voltage of
that particular loop it should be equal.
7.
In case of no voltage source in loop take the sum of all voltage source equal to
zero.
8.
Repeat above procedure for loop BCHI, CDGH, DEFG.
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Experiment 6
Objective :
Study of the R-C circuit and find out the behavior of capacitor in a R-C network
and study the phase shift due to capacitor.
Theory :
The Capacitor : A capacitor is a device that can store electrical charge. The simplest
kind is a "parallel plate" capacitor that consists of two metal plates that are separated
by an insulating material such as dry air, plastic or ceramic. Such a device is shown
schematically below figure 18.
A simple capacitor circuit
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Figure 18
It is straightforward to see how it could store electrical energy. If we connect the two
plates to each other with a battery in the circuit, as shown in the figure above, the
battery will drive charge around the circuit as an electric current. But when the
charges reach the plates they can't go any further because of the insulating gap; they
collect on the plates, one plate becoming positively charged and the other negatively
charged. The voltage across the plates due to the electric charges is opposite in sign to
the voltage of the battery. As the charge on the plates builds up, this back-voltage
increases, opposing the action of the battery. As a consequence, the current flowing in
the circuit decays, falling to zero when the back-voltage is exactly equal and opposite
to the battery voltage.
If we quickly remove the wires without touching the plates, the charge remains on the
plates. Because the two plates have different charge, there is a net electric field
between the two plates. Hence, there is a voltage difference between the plates. If,
sometime later, we connect the plates again, this time with a light bulb in place of the
battery, the plates will discharge: the electrons on the negatively charged plate will
move around the circuit to the positive plate until all the charges are equalized.
During this short discharge period a current is flowing and the bulb will light. The
capacitor stored electrical energy from its original charge up by the battery until it
could discharge through the light bulb. The speed with which the discharge (and
conversely the charging process) can take place is limited by the resistance of the
circuit connecting the plates and by the capacitance of the capacitor (a measure of its
ability to hold charge).
An RC circuit is simply a circuit with a voltage source (battery) connected in series
with a resistor and a capacitor.
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Charging
Discharging
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Figure 19
As with circuits made up simply of resistors, electrical currents can flow in this RC
circuit, with one modification. A battery connected in series with a resistor will
produce a constant current. The same battery in series with a capacitor will produce a
time varying current, which decays gradually to zero. If the battery is removed and the
circuit reconnected without the battery, a current will flow (for a short time) in the
opposite direction as the capacitor "discharges". A measure of how long these
transient currents last in a given circuit is given by the "time constant", τ.
The time it takes for these transient currents to decay depends on the resistance and
capacitance. The resistor resists the flow of current ⇒ slows down the decay. The
capacitance measures capacity to hold charge: like a bucket of water, a larger capacity
container takes longer to empty than a smaller capacity container. Thus, the "time
constant" of the circuit gets larger for larger R and C. In detail:
τ (seconds) = R(Ohms) × C(Farads)
Charging
Discharging
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Figure 20
Procedure :
1.
Connect the circuit as shown in figure
a. Connect +ve end of DC power supply to one end of switch.
b. Connect centre terminal of switch to 100KΩ resistor.
c. Connect other end of resistor to +ve end of capacitor.
d. Connect –ve terminals of DC power supply and capacitor with each other.
Figure 21
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2.
Switch ‘On’ the trainer board.
3.
Put the toggle switch in ‘Off’ condition, if there is some remaining voltage on
the capacitor, use a piece of wire to short the two leads together draining any
remaining charge, i.e. discharge the capacitor.
4.
Now if you put the toggle switch in ON condition you can observe voltmeter
that the capacitor is charging very fast but after few second the rate of charging
is slow.
5.
Now put the toggle switch in ‘Off’ condition and connect a wire from 1st end of
resistor to 2nd end of capacitor. Here we can observe the charge is flowing back.
In start it discharges very fast but after few seconds discharging is slow.
6.
You can record the time of charging tc and time of discharging td for a given
value of resistor and capacitor. Now you can change the value of resistors and
capacitors and record the values of tc and td in the table.
No.
Resistance
Capacitance
tc
td
1
3
4
Phase Shift :
1.
Replace the electrolytic capacitor of previous circuit with metallic polyester
capacitor 0.1µf.
2.
Now replace the DC supply with AC supply as shown in figure
3.
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2
Now measure the voltage across the resistor and capacitor both.
4.
You will found that the voltage drop across the resistor = ………V and across
the capacitor = ……… V. i.e. it do not add up to equal the total voltage of 6V.
This is due to phase shift in the circuit, voltage dropped across the capacitor is
out of phase with voltage drop across the resistor, and thus the voltage drop
figures do not add up as one might expect.
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Figure 22
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Experiment 7
Objective :
Study of the L-C circuit and its oscillations.
Theory :
Let us assume that initially the capacitor C of the LC circuit carries a charge Q and
the current I in the inductor is zero.
At this instant, the energy stored in the electric field of the capacitor is
 Q2 
 . The energy stored in the inductor is zero.
UE = 
 2C 
The capacitor now begins to discharge through the inductor. The current begins to
flow counter-clockwise. As the charge on the capacitor decreases, UE decreases. But
1

the energy UB =  LI 2  in the magnetic field of the inductor increases. The energy
2

is transferred from the capacitor to the inductor.
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The energy stored in the capacitor is transferred entirely to the magnetic field of the
inductor. At this stage, there is maximum value of current in the inductor. This current
continues to transport positive charge from the top plate of the capacitor to the bottom
plate of the capacitor. Energy now flows from the inductor back to the capacitor as the
electric field builds up again.
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The capacitor will begin to discharge again. The current will now flow clockwise.
Proceeding as before, we find that the circuit eventually returns to the situation
depicted. The process continues at a definite frequency. The energy is continuously
shuttled back and forth between the electric field in the capacitor and the magnetic
field in the inductor.
Procedure :
1.
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In an actual LC circuit, some resistance is always present. This resistance will drain
energy from the electric and magnetic fields and dissipate it as thermal energy will not
continue indefinite
Connect the circuit as shown in figure
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Figure 23
a.
Connect the positive terminal of DC power supply to one ends of capacitor
0.1µf and an inductor coil (800 turn).
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b. Connect other end of capacitor to negative of DC power supply through a
switch (1st and common end of switch)
c.
2.
Connect other end of coil to third end of switch (which acts as a second
switch).
It is a LC circuit as you switch ‘On’ the trainer board and continuously switch
‘On’ and ‘Off’ the toggle switch. You can observe the oscillations in
oscilloscope. Because if an inductor and a capacitor are connected in parallel
with each other and then power is feeded by a DC voltage source, oscillations
will ensure as energy is exchanged from the capacitor to inductor and vice
versa. Parallel inductor/ capacitor circuits are known as Tank circuit. Its natural
frequency is called resonant frequency and can be determined with the help of
following formula.
 1 
Frequency = 

 2π LC 
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F = ……..... Hz
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Figure 24
So here,
L = ……….. mH
C = 0.1µf
Keep CRO’s time base position at 0.2ms and try to get oscillations on CRO by
adjusting the level potentiometer in normal mode.
Now you can change the value of L and C and can observe the results in CRO.
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Experiment 8
Objective :
Study of the characteristics of a semiconductor diode.
Theory :
A diode is an electrical device allowing current to move through it in one direction
with far greater ease than in the other. The most common type of diode in modem
circuit design is the semiconductor diode, although other diode technologies exist.
Semiconductor diodes are symbolized in schematic diagrams as shown below
Figure 25
When placed in a simple battery-lamp circuit, the diode will either allow or prevent
current through the lamp, depending on the polarity of the applied voltage:
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V-I Characteristic :
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Figure 26
When the polarity of the battery is such that electrons are allowed to flow through the
diode, the diode is said to be forward-biased. Conversely, when the battery is
"backward" and the diode blocks current, the diode is said to be reverse biased. A
diode may be thought of as a kind of switch: "closed" when forward-biased and
"open" when reverse-biased.
The static voltage-current characteristics for a P-N Junction diode are shown in figure
Forward Characteristic :
Reverse Characteristic :
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When the diode is in forward-biased and the applied voltage is increased from zero,
hardly any current flows through the device in the beginning. It is so because the
external voltage is being opposed by the internal barrier voltage VB whose value is 0.7
V for Si and 0.3 V for Ge. As soon as VB is neutralized, current through the diode
increases rapidly with increasing applied supply voltage. It is found that as little a
voltage as 1.0 V produces a forward current of about 50mA.
When the diode is reverse-biased, majority carrier are blocked and only a small
current (due to minority carrier) flows through the diode. As the reverse voltage is
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increased from zero, the reverse current very quickly reaches its maximum or
saturation value Io which is also known as leakage current. It is of the order of
nanoamperes (nA) and microamperes (µA) for Ge.
Procedure :
1.
Connect the circuit as shown in figure 27.
Connect +ve terminal of DC power supply to one end of potentiometer.
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a.
Figure 27
b. Connect middle terminal of potentiometer to one end of resistor 1K.
c.
Connect other terminal of resister to +ve end (Black end) of diode IN4007.
d. Connect –ve terminal of DC power supply to other end of potentiometer.
on
2.
Now rotate the potentiometer fully clockwise position.
3.
Connect one multimeter (at voltmeter range) point A and B it means across the
diode.
4.
Now connect the multimeter (as ammeter) between –ve terminal of diode and
ground, it means we have to connect it in series with diode.
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Figure 28
Switch ‘On’ the power supply.
6.
Vary the potentiometer so as to increase the value of diode voltage VD in the
steps of 100mV.
7.
Now record the diode current ID (mA) with corresponding diode voltage VD in
table.
S. No.
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Diode Voltage
VD
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Diode Current
ID (mA)
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8.
Plot a curve between diode voltage VD and current ID as shown in figure (1st
quadrant) using suitable scale with the help of observation table. This curve is
required forward characteristics of Si diode.
Figure 29
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For Reverse Characteristics :
For this experiment only the polarity of diode will be reversed.
1.
Measure the diode voltage VD in steps of 1 Volt, and corresponding diode
current same as the previous given procedure.
2.
Plot a curve between diode voltage VD and diode current ID as shown in figure
29 (3 rd quadrant). This curve is required characteristics of Si diode.
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Experiment 9
Objective :
Study of the characteristics of a transistor.
Theory :
Transistor characteristics are the curves, which represent relationship between
different dc currents and voltages of a transistor. These are helpful in studying the
operation of a transistor when connected in a circuit. The three important
characteristics of a transistor are:
1.
Input characteristic.
2.
Output characteristic.
3.
Constant current transfer characteristic.
Input Characteristic :
Figure 30
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Output Characteristic :
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In common emitter configuration, it is the curve plotted between the input current (IB)
verses input voltage (VBE) for various constant values of output voltage (VCE).
The approximated plot for input characteristic is shown in figure 30. This
characteristic reveal that for fixed value of output voltage VCE, as the base to emitter
voltage increases, the emitter current increases in a manner that closely resembles the
diode characteristics.
This is the curve plotted between the output current IC verses output voltage VCE for
various constant values of input current IB.
The output characteristic has three basic region of interest as indicated in figure 31.
The active region, cutoff region and saturation region.
In active region the collector base junction is reverse biased while the base emitter
junction if forward biased. This region is normally employed for linear (undistorted)
amplifier.
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In cutoff region the collector base junction and base emitter junction of the transistor
both are reverse biased. In this region transistor acts as an ‘Off’ switch.
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Figure 31
In saturation region the collector base junction and base emitter junction of the
transistor both are forward biased. In this region transistor acts as an ‘On’ switch.
Constant current transfer Characteristics :
on
This is the curve plotted between output collector current IC verses input base current
IB for constant value of output voltage VCE. The approximated plot for this
characteristic is shown in figure 32.
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Figure 32
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Procedure :
Circuit used to plot different characteristics of transistor is as follows.
Common emitter (NPN) configuration
Figure 33
Input Characteristics :
For these experiments you must have an external power supply of +12V.
2.
Connect +ve end of +5V supply to one end of 10K potentiometer.
3.
Connect center end of pot P1 to a resistor 5KΩ.
4.
Connect BC547 transistor to the trainer board.
5.
Connect other end of resistor to base of transistor.
6.
Connect emitter of transistor to –ve end of +5V supply and to third end of
potentiometer.
7.
Rotate the potentiometer in fully counter clockwise position.
8.
Now connect collector of transistor to a resistor 100Ω and other end of resistor
to center end of other 10K pot. (which is supplied in component box)
9.
Connect a external +12V supply to other ends of potentiometer P2 and switch
‘On’ the trainer board.
10.
Connect a voltmeter across collector and emitter of transistor and set VCE at
some constant value say 1V with the help of P2.
11.
Now vary the potentiometer P1 so as to increase the value of I/P voltage VBE
(across base and emitter of transistor) from 0 to 0.8V in steps and measure the
corresponding values of I/P current IB by connecting a ammeter in series
between resistor 5K and base of transistor.
12.
Repeat the above procedure for different constant values of VCE.
13.
Now plot a curve between I/P voltage VBE and I/P current IB as shown in theory
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Observation Table :
S. No.
Input voltage
VBE
1.
0.0V
2.
0.1V
3.
0.2V
4.
0.3V
5.
0.4V
6.
0.5V
7.
0.6V
Input current IB (uA) at constant
value of output voltage
VCE = 1V
VCE = 3V
VCE =5V
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8.
0.7V
9.
0.8V
Output Characteristics :
on
Switch ‘Off’ the supply.
2.
Rotate both the potentiometer P1 and P2 in fully counter clockwise position.
3.
Switch ‘On’ the power supply.
4.
Vary the potentiometer and set a value of I/P current IB at some constant value
say (0µA, 10µA, ….. 100µA) by connecting a meter between resistor 5K and
base of transistor.
5.
Vary the potentiometer P2 so as to increase the value of O/P voltage VCE from 0
to maximum value in steps and measure the output current IC by connecting
ammeter between collector of transistor and 100Ω resistor.
6.
Repeat the procedure for different values of I/P current IB.
7.
Plot a curve between O/P voltage VCE and O/p current IC as shown in theory.
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Observation Table :
S.no.
Output voltage
VCE
1.
0.0V
2.
0.5V
3.
1.0V
4.
2.0V
5.
3.0V
6.
4.0V
7.
5.0V
9.
10.
IB = 0uA IB =10uA IB =20uA IB =30uA IB =40uA
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8.
Output current IC (mA) at constant value of
input current
6.0V
7.0V
8.0V
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Experiment 10
Objective :
Understanding the Faraday’s Law of electromagnetic induction.
Whenever there is a change in the magnetic flux linked with a circuit an emf and
consequently a current is induced in the circuit. However, it lasts only so long as the
magnetic flux is changing.
Procedure :
1.
Figure 34
Now take a bar magnet and keep its north pole stationary near one end of coil as
shown in figure 34. The galvanometer shall not show any deflection. When
magnet is stationary.
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2.
Take any coil from the given coil set and let the two ends of the coil be
connected to the two terminal of galvanometer.
When the magnet is moved toward the coil, the galvanometer shows deflection
as shown in figure 35.
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4.
Figure 35
When the magnet is moved away from the coil, the galvanometer again shows
deflection but in opposite direction.
Similar results are obtained when the magnet is kept stationary and the coil is
moved.
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6.
When the magnet is moved slowly the deflection in meter is small, but when the
magnet is moved fast the deflection is large.
7.
It is clear from above experiment that when magnetic flux. Changes through a
coil, a current are induced in the coil.
8.
Observe the results for different coils.
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Experiment 11
Objective :
Study of the behavior of current when inductance is introduced in the circuit.
Procedure :
1.
Connect the following circuit.
a.
Figure 36
Connect AC power supply with a one end of coil (800 turn) and other end
to a light bulb.
b. Connect other end of light bulb to other end of AC power supply.
Now as you switch ‘On’ the trainer board, you can observe that light bulb is
glowing with good intensity.
3.
Take I-core and insert in the coil, result will be the light of decreased intensity.
4.
The glow of the bulb will decrease because, as the iron rod is inserted in the coil
its inductance increases so inductive reactance increase. This result in an
increase in impedance of the circuit. Consequently, the current in the circuit
decreases and hence the glow of the bulb decreases.
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Experiment 12
Objective :
Study of the Lenz’s Law and effect of eddy current.
The induced current produced in the conductor always flows in such a direction that
the magnetic field it produces will oppose the change that is producing it.
Lenz’s law states that in a given circuit with an induced emf caused by a change in a
magnetic flux, the induced emf causes a current to flow in the direction that oppose
the change in flux. That is if a decreasing magnetic flux induces an emf, the resulting
current will oppose a further decrease in magnetic flux. Likewise for an emf induced
by an increasing magnetic flux, the resulting current flows in a direction that opposes
a further increase in magnetic flux. ‘when the north pole of the magnet is moved
towards the coil, the direction of the induced current in the coil will be such that the
upper face of the coil acquired north polarity. So the coil repels the magnet.
In other words, the coil oppose the motion of the magnet towards itself which is really
the cause of the induced current in the coil. Similarly, if the south pole of a magnet is
moved towards the coil, the upper face of the coil will acquire south polarity there by
opposing the motion of the magnet.
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Eddy Current :
on
Eddy current may be defined as current induced in a thick conductor when the
conductor is placed in a changing magnetic field. Consider a metal block placed in a
continuously varying magnetic field. The magnetic field can be changed either by
having a permanent magnetic field and moving the block in and out of it or by
keeping the block fixed and changing the magnetic field with the help of an
alternating current. Due to the continuous change of magnetic flux linked with the
metal block, induced current will be setup in the body of the metal block itself.
Procedure :
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These current assume a circular path and their direction is given by Lenz’s law. These
current look like eddies in a fluid and hence called eddy current. Since the resistance
of this conductor is quite low therefore the eddy current are generally quite large in
magnitude and produces heating effect. In following experiment, we will see its
effect.
Take a 400 turn coil.
2.
Fix a U-core into the bracket given on the trainer board.
3.
Insert the coil in any end of U core.
4.
Connect one end of coil to positive terminal of DC power supply and other to
the one terminal of switch.
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Figure 37
Connect –ve terminal of power supply to other end of switch.
6.
Let the toggle switch in ‘Off’ (upward direction if first two terminals are used)
condition.
7.
Take a soft iron square piece from the accessories and put it on the upper base
of U-core where coil is connected.
8.
Switch ‘On’ the trainer board. As you switch ‘On’ the toggle switch the metallic
piece is thrown up. Because when the current begins to grow through the coil,
the magnetic flux through the core and hence metallic piece begins to increase.
This sets up eddy currents in the metallic piece. If the upper face of the core
acquires N polarity in it then the lower face of the metallic piece also acquires N
polarity according to the Lenz’s law. Due to force of repulsion between same
poles, the metallic piece is thrown up.
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Experiment 13
Objective :
Study of the relay and construction of a switching circuit by using relay.
A relay is a electrical switch that opens and closes under control of another electrical
circuit. In the original form the switch is operated by an electromagnet to open or
close one or many sets of contacts. Generally relay is having following terminals and
contacts.
1.
Input Coil : Operating voltage for relay is feeded to it.
2.
Normally closed (NC) Contact : It disconnect the circuit when the relay is
activated.
3.
Normally Open Contact (NO) : It connect the circuit when the relay is activated.
4.
Pole : It is the common terminal between NC and NO.
Procedure :
1.
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When a current flows through the coil, the resulting magnetic field attracts an
armature that is mechanically linked to a moving contact. The movement either makes
or breaks a connection with a fixed contact. When the current to the coil is switched
off, the armature is returned by a force that is half as strong as the magnetic force to
its relaxed position.
Figure 38
Connect the circuit as shown in following figure 39.
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Figure 39
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a.
Connect positive terminal of DC power supply to one end of coil and
negative terminal to other end of coil through a toggle switch.
b. Connect pole to any one terminal of AC power supply.
c.
Connect NO terminal to one end of Buzzer and NC terminal of relay to one
end of a light bulb.
d. Connect other end of AC power supply with other ends of Buzzer and light
bulb.
Keep the toggle switch in off condition.
3.
Now switch ‘On’ the power supply. In this condition relay coil is not getting
supply voltage so the pole and NC terminals are shorted with each other and
since we have connected a light bulb with this terminals in series with a AC
power supply so it gets lightened.
4.
Now as you turn ‘On’ the toggle switch, coil of relay will get supply voltage
=5V and hence the NC point of relay is separated from pole and NO point of
relay attracted towards pole and make contact with pole. Since we have
connected a buzzer with these terminals in series with an AC power supply so
buzzer gives the sound of frequency 50 Hz.
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Experiment 14
Objective :
Study of the Oersted experiment.
The connection between electricity and magnetism was rediscovered by a Danish
physicist Hans Christian Oersted in 1820. During a lecture demonstration, Oersted
observed that a magnetic compass needle aligned itself perpendicular to a currentcarrying wire. Oersted also noticed that when the direction of current in the wire was
reversed, the direction in which the needle was pointed was also reversed. These
observations led Oersted to conclude that a magnetic field is associated with an
electric current.
The quantitative consequences of a steady current flow were established by four
French physicists. Francois Arago demonstrated that a current-carrying wire behaves
like an ordinary magnet in its ability to attract iron filings. Andre Marie Ampere
discovered that current-carrying wires exert forces of attraction or repulsion on each
other. He also determined the laws governing, these interactions. Jean-Baptise Biot
and Felix Savart determined experimentally the magnitude and direction of the
magnetic field due to small current element.
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Procedure :
1.
Take a 800 turn coil (or any one from the coil set).
2.
Connect it to DC power supply as shown in figure 40.
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Figure 40
Switch ‘On’ the trainer board.
4.
Now put magnetic compass near the coil, you can observe the deflection of the
needle.
5.
Now inter change the connection of coil. So the direction of current will be
changed.
6.
Now you can observe needle is also deflected reversely. This is the Oersted’s
experiment.
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7.
Experiment 15
Objective :
Study of the phenomenon of mutual induction.
Theory :
Phenomenon : If a varying current is flowing in the coil than an induced emf is
produced in the neighboring coil. It means it is the property of two coils due to which
each opposes any change in current flowing in the other by developing an induced
emf.
Procedure :
1.
Take 200 turn, 3200 turn coil and a U-core from the given accessories.
2.
Fit the U-core on the bracket given on trainer board.
3.
Place the 200 turn coil in U – core as primary and 3200 turn coil as secondary
winding.
4.
Now connect the one end of 200 turn coil to positive terminal of DC power
supply and other end to a terminal of switch, as shown in following figure 41.
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5.
Figure 41
Make common to the negative terminal of DC power and other terminal of
switch.
Connect one terminal of secondary coil to the galvanometer and other terminal
to second terminal of galvanometer.
7.
Now switch ‘On’ the trainer board and toggle switch, in the circuit. As the
switch is ON the pointer of galvanometer will gives a sudden kick in one
direction, say to the left.
8.
Now when the toggle switch is turned off the galvanometer will give deflection
to the right.
9.
We have observed that when switch is ON the current in the primary being to
increase from zero to maximum. During the growth of current the magnetic flux
linked with the primary beings to increase and since secondary is vary near to
primary coil so its linked magnetic flux is also increases. Hence current is
induced in secondary.
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10.
Now according to Lenz’s law the direction of current in secondary is such as to
oppose the growth of power supply current in the primary, so the deflection of
galvanometer is because of secondary induced current. When the switch is
turned ‘Off’ the current in the primary coil beings to decrease towards zero. So
the magnetic flux linked with primary and as well as secondary also decrease.
Because of that an induced current flows in secondary. According to Lenz’s law
the direction of current should be such as to oppose the decrease of current in
the primary and this is possible only if the induced current flows in same
direction as the power supply current in the primary. That is why the
galvanometer gives deflection to the right direction at the time of break of
circuit.
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11.
Experiment 16
Objective :
Construction and study of the step down transformer with the help of given coils
and cores.
Theory :
Transformer is working on the principle of electromagnetic induction i.e. when
current in one circuit changes, an induced current is set up in the neighboring circuit.
It consists of two coils primary and secondary. These coils are insulated from each
other and wound over the same core. In order to avoid eddy currents the core is
laminated. The alternating electrical energy is supplied to the primary coil. The output
electrical energy is drawn from the 2nd coil. In the step down transformer the primary
coil consists of a large number of turns of fine insulated copper wire. The secondary
coil consists of few turns of thick insulated copper wire. In step up transformers the
primary coil consists of few turns of thick insulated copper wire and the secondary
coil consists of large number of turns of fine insulated copper wire. In these types of
transformers the core is largely surrounded by coils.
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The transformer makes use of faraday’s law and Ferro magnetic properties, of an iron
core to efficiently raise or lower AC voltages. It of course cannot increase the power
so that if the voltage is raised the current is proportionally lowered and vice-versa.
Figure 42
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For an Ideal transformer the voltage ratio is equal to the turns ratio and power in
equals to the power out. It means
1.
Where,
Vs = Secondary voltage
Vp = Primary voltage
Ns = No. of turns in secondary coil
Np = No. of turns in primary coil
Pp = VpIp = VsIs = Ps.
Procedure :
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2.
Vs = Ns
Vp
Np
1.
Take two 400 turn coils from the coil set.
2.
Take U shaped core and fit it on the trainer board with the help of screws.
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3.
Now insert one 400 turn coil in U core as a primary coil and other as a
secondary coil. Also put I shaped core on the U core to complete the flux
linkages.
4.
Connect primary coil to the DC power supply.
5.
Measure the secondary voltage with the help of multimeter.
6.
Observe the result there will be no output voltage.
7.
Now change the power supply from DC to AC.
8.
Now measure the secondary voltage in multimeter there will be some reading.
Note : These are not ideal transformers. Since coils are not coaxially wound on
the same core the losses are more or the voltage transformation ratio is
proportionately below the ideal values based on number of turns per coil. But
effective quantitative investigation can be done with the help of this set upto
20% loss may be obtained from desire voltage.
Note the reading (ideally it should be same as input voltage because number of
turns are same). Also note the percentage of losses. It will be helpful for further
pairs of coils and for their calculations.
10.
Now connect 200 turn coil in secondary and measure the voltage. You can
observe the voltage is lowered.
11.
In the same way you can connect any large number of coil as a primary and can
record the results for different lower turns secondary coils in the table.
12.
Now you can change the type of core and observe the results.
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9.
No. of turns
Primary Coil
Secondary Coil
400
400
800
400
800
200
1600
800
1600
400
1600
200
3200
1600
3200
800
3200
400
3200
200
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6V
6V
6V
6V
6V
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I/P Voltage
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Type of
Core
6V
6V
6V
6V
6V
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Experiment 17
Objective :
Construction and study of the step up transformer.
Procedure :
1.
Repeat step 1 to 9 from the previous experiment of step down transformer.
2.
Now connect 800 turn coil in the circuit as secondary coil. Observe the result,
the voltage is higher than that of input voltage 6V.
3.
Now you can connect any combination of a lower turn primary coil and large
turns secondary coil.
4.
Record the result in the given table.
5.
Now observe the result by changing the core.
No. of turns
Primary Coil
400
400
800
800
1600
200
6V
800
6V
1600
6V
3200
6V
1600
6V
3200
6V
3200
6V
400
6V
800
6V
200
1600
200
3200
6V
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400
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AC
I/P Voltage
Secondary Coil
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Type of
Core
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Experiment 18
Objective :
Study of the effects of moving I core on a step up transformer.
Procedure :
Take U core and fit it on the trainer board.
2.
Take a 400 turn coil and insert it into the U core as primary coil.
3.
Take a 800 turn coil and insert it into the U core as secondary coil.
4.
Now take a U shape small object and I core with the long screw from the
accessories box.
5.
Now fit the object on U core in such a way that the long screw of I core should
be matched with the given hole on the object. (when I-core is placed on U-core)
6.
Tight the bottom screw of object at its extreme and upper screw of object
slightly less than its extreme position.
7.
Now if you move long screw, of I-core the I-core will move from its position
towards upper or lower direction.
8.
Now connect primary coil to 6V AC power supply and secondary to multimeter.
Switch ON the trainer.
9.
If you move the screw, I-core will move and because of that power linkages will
be changed and can be observed in multimeter.
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1.
If a light bulb is connected across the secondary the effect of moving the I-core can be
demonstrated to the students.
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Figure 43
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Experiment 19
Objective :
Conversion of a galvanometer into voltmeter.
Theory :
A galvanometer can be converted into a voltmeter by connecting a high resistance in
series with it
Let
G = Resistance of the galvanometer.
V = Potential difference to be measured.
Ig = Current for full scale deflection in the galvanometer.
R = High resistance connected in series with the galvanometer.
Figure 44
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Now by applying ohm’s law V = Ig(G+R) or V = G+R or
Ig
R=V-G
Ig
It means if the potential difference V to be measured exceeds IgG then a suitable
resistance R is required to be connected in series with the galvanometer to use
galvanometer as a voltmeter of range (0-v).
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Procedure :
For making galvanometer conversion into voltmeter of range 0 – 5V for this we
know that
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R = Unknown series resistance that we have to find out.
V = 5V
Ig = Curent required for full scale deflection of galvanometer.
G = 80 Ω galvanometer resistance.
First we will measure Ig current. For this connect following circuit.
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Figure 45
a.
Connect positive terminal of DC power supply to a 1K resistor and
negative to a terminal of galvanometer.
b. Connect other end of resistor to positive terminal of ammeter and negative
terminal to one end of potentiometer.
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c.
Set the potentiometer fully clockwise direction.
d. Connect other end of galvanometer and potentionmeter with each other.
Now as you switch ‘On’ the trainer board you can observe some deflection in
galvanometer, now adjust the potentiometer such that to get full scale deflection
of needle.
4.
Now measure the current in ammeter at the full scale deflection position,
It is say – Ig = 0.74 mA
So
R=
5v -G
Ig
R=
5 v - 80 Ώ
.74 mA
R=
5v
- 80
-3
0.74 x 10
R=
6756 – 80
R = 6676 = 6.6K approx.
5.
Now disconnect the circuit and adjust the potentiometer at 6.6 kΩ position with
the help of multimeter.
6.
Now connect the circuit as follows to convert galvanometer into voltmeter and
to test it.
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3.
Figure 46
You can observe that now galvanometer is showing FSD. It means it is
calibrated for range 0 – 5V.
8.
Now make the 2.5V supply with the help of 5V by using resistances, as follows
9.
Figure 47
If you connect 2.5V supply to point A and B as shown in above figure 47, the
deflection of the needle should be in mid position.
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Experiment 20
Objective :
Conversion of a galvanometer into ammeter.
Theory :
A galvanometer can be converted into ammeter by connecting parallel resistances of
low value called shunt.
Figure 48
Potential difference across the galvanometer = IgG
Potential difference across the shunt = (I-Ig) S
Since both are connected in parallel so both should be equal (I-Ig)S = IgG
I – Ig
=
=
=
=
Unknown current that we have to measure
Current required to galvanometer for FSD
Galvanometer resistance
Shunt resistance that we have connect in parallel to galvanometer
on
Where
I
Ig
G
S
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S = Ig G
Procedure :
For making galvanometer conversion into ammeter of range 0 – 50 mA
1.
S = 0.74 x 10 -3 x 80
(50 – 0.74) x 10 -3
S = 59.2 /49.26
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For this we know that
S = IgG
I-Ig
S = Unknown resistance that we have to find out.
Ig = We have already calculated it, in previous experiment = 0.74mA
(approx.)
I = Unknown current to be measured.
G = 80 Ω
Now
S = 0.74mA x 80
50mA – 0.74mA
S = 1.2 Ω
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2.
Now adjust the potentiometer 25E given on trainer board to the vale of 1.2 Ω
with the help of multimeter and connect it to the parallel of galvanometer as
shown in following figure 49.
3.
Now if you want to have 50 mA current in the circuit of supply 5V than you
have to connect 100 Ω resistance accesses it from ohm’s law.
4.
Adjust the potentiometer (10K) for value = 100Ω.
5.
Now as you switch ‘On’ the trainer board you can observe the needle is having
full scale deflection. It means now the galvanometer is calibrated for range 0-50
mA.
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Figure 49
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Now if you increase the resistance from 100 Ώ to 200 Ώ (Pot 10 K) then the current
will be just half of the previous case i.e., 25mA and you can observe the pointer of the
galvanometer is deflected upto the mid position.
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Experiment 21
Objective :
Study of the Hysteresis curve.
Equipments Needed :
1.
Function Generator
2.
CRO
3.
100K ohm and 10 ohm resistance
4.
E, I core
5.
400 and 3200 Turn coils
6.
Patch cords etc.
Theory :
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A great deal of information can be learned about the magnetic properties of a material
by studying its hysteresis loop. A hysteresis loop shows the relationship between the
induced magnetic flux density (B) and the magnetizing force (H). It is often referred
to as the B-H loop. An example hysteresis loop is shown below.
Figure 50
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The loop is generated by measuring the magnetic flux of a ferromagnetic material
while the magnetizing force is changed. A ferromagnetic material that has never been
previously magnetized or has been thoroughly demagnetized will follow the dashed
line as H is increased. As the line demonstrates, the greater the amount of current
applied (H+), the stronger the magnetic field in the component (B+). At point "a"
almost all of the magnetic domains are aligned and an additional increase in the
magnetizing force will produce very little increase in magnetic flux. The material has
reached the point of magnetic saturation. When H is reduced to zero, the curve will
move from point "a" to point "b." At this point, it can be seen that some magnetic flux
remains in the material
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Figure 51
Procedure :
Connect the circuit as shown in above figure 51.
2.
Make a transformer using E, I core and 400 and 3200 turn coils.
3.
Connect 10 ohm and 100Kohm resistors as shown in figure 51.
4.
Connect a capacitor 100μF as shown in circuit.
5.
Set CRO on XY - mode.
6.
Connect a sine wave signal from Function generator and adjust Voltage and
frequency of sine wave as
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1.
Voltage:-30Vpp
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Frequency:-50Hz
7.
Connect 1 and 2 terminal of circuit to X - channel and 3 and 4 terminals Y channel of CRO.
8.
Set the vertical sensitivity as follows :
CHI-20m V
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CH2-20mV
By varying frequency 1 Hz to 50 Hz and voltage, you can study the change in
hysteresis loop.
10.
If we change the voltage of input signal it means we are changing (H) magnetic
force, and then magnetic flux (B) density also changes according to change in
magnetic force. In this way we can study relation between H and B.
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9.
Even though the magnetizing force is zero. This is referred to as the point of
retentivity on the graph and indicates the remanence or level of residual magnetism in
the material. (Some of the magnetic domains remain aligned but some have lost their
alignment.) As the magnetizing force is reversed, the curve moves to point "c", where
the flux has been reduced to zero. This is called the point of coercivity on the curve.
(The reversed magnetizing force has flipped enough of the domains so that the net
flux within the material is zero.) The force required to remove the residual magnetism
from the material is called the coercive force or coercivity of the material.
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As the magnetizing force is increased in the negative direction, the material will again
become magnetically saturated but in the opposite direction (point "d"). Reducing H
to zero brings the curve to point "e." It will have a level of residual magnetism equal
to that achieved in the other direction. Increasing H back in the positive direction will
return B to zero. Notice that the curve did not return to the origin of the graph because
some force is required to remove the residual magnetism. The curve will take a
different path from point “F” back to the saturation point where it with complete the
loop.
From the hysteresis loop, a number of primary magnetic properties of a material can
be determined.
Retentivity : A measure of the residual flux density corresponding to the
saturation induction of a magnetic material. In other words, it is a material's
ability to retain a certain amount of residual magnetic field when the
magnetizing force is removed after achieving saturation. (The value of B at
point b on the hysteresis curve.)
2.
Residual Magnetism or Residual Flux : the magnetic flux density that
remains in a material when the magnetizing force is zero. Note that residual
magnetism and retentivity are the same when the material has been magnetized
to the saturation point. However, the level of residual magnetism may be lower
than the retentivity value when the magnetizing force did not reach the
saturation level.
3.
Coercive Force : The amount of reverse magnetic field which must be applied
to a magnetic material to make the magnetic flux return to zero. (The value of H
at point c on the hysteresis curve.)
4.
Permeability, µ : A property of a material that describes the ease with which a
magnetic flux is established in the component.
5.
Reluctance - Is the opposition that a ferromagnetic material shows to the
establishment of a magnetic field. Reluctance is analogous to the resistance in
an electrical circuit.
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Warranty
1)
We guarantee the product against all manufacturing defects for 24 months from
the date of sale by us or through our dealers. Consumables like dry cell etc. are
not covered under warranty.
2)
The guarantee will become void, if
a)
The product is not operated as per the instruction given in the operating
manual.
b)
The agreed payment terms and other conditions of sale are not followed.
c)
The customer resells the instrument to another party.
d)
Any attempt is made to service and modify the instrument.
3)
The non-working of the product is to be communicated to us immediately giving
full details of the complaints and defects noticed specifically mentioning the
type, serial number of the product and date of purchase etc.
4)
The repair work will be carried out, provided the product is dispatched securely
packed and insured. The transportation charges shall be borne by the customer.
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2.
Parch cord 2mm to 2mm (10”) .............................................................. 10 Nos.
3.
Coils 200, 800, 1600, 3200 turns.............................................................. 1 each
4.
400 turn coil............................................................................................. 2 Nos.
5.
Bar magnet ................................................................................................1 No.
6.
Magnetic compass......................................................................................1 No.
7.
U, E, I core .............................................................................................. 1 each
8.
I core with long screw ................................................................................1 No.
9.
Pieces of soft iron .................................................................................... 5 Nos.
10.
Component box
Resistances :
100 Ω .............................................................................................. 15 Nos.
200 Ω .............................................................................................. 10 Nos.
220 Ω ............................................................................................... 10 Nos.
332 Ω .............................................................................................. 10 Nos.
1KΩ ................................................................................................. 10 Nos.
100 KΩ............................................................................................. 10 Nos.
220 KΩ............................................................................................. 10 Nos.
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1.
List of Accessories
Mains cord.................................................................................................1 No.
5 KΩ .................................................................................................. 2 Nos.
Potentiometer 10 K ....................................................................................1 No.
12.
Electrolytic capacitor 100µf .................................................................... 2 Nos.
13.
Metalized poly. Capacitor 0.1µf............................................................... 2 Nos.
14.
Diode (1N4007)....................................................................................... 5 Nos.
15.
Transistor (BC547) .................................................................................. 5 Nos.
16.
Multimeter ................................................................................................1 No.
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