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POLYTECHNIC OF KOTA BHARU
DEPARTMENT OF ELECTRICAL ENGINNERING
ET101 – ELECTRICAL TECHNOLOGY
EXPERIMENT 4
TOPIC
: KIRCHHOFF’S LAWS
OBJECTIVE
: To verify Kirchhoff’s voltage e and current laws experimentally.
THEORY
:
Kirchhoff’s Voltage Law ( KVL) :
The algebraic sum of all voltage around any closed path is equal To
zero.
Kirchhoff’s Current Law ( KCL) :
The algebraic sum of all current at a junction point is equal to zero.
EQUIPMENTS:
DC Power Supply
DC Ammeter
DC Voltmeter
Resistor 100Ω, 150Ω, 220Ω and 330Ω.
PROCEDURES:
1. Check the value of the resistor, used in the circuit of Figure 1, using multimeter. Record the
values in Table 1.
2. Connect the circuit as shown, and have it checked by instructor. Adjust the supply voltage
Vs to 10 V, using a dc voltmeter.
3. Measure the voltages VAB, VBC, VAD, VDC, VBD and VAC. Record their values (including the
signs) in Table 2.
4. Measure the currents I1, I2, I3, I4, and I5 and record their values (including the signs) in
Table 3.
1
F
A
I5
I3
I1
220 ohm
Vs = 10 V
100 ohm
D
B
150 ohm
E
330 ohm
I4
I2
C
Figure 1
RESULTS :
i.
By Theory
1. Verify KVL by adding the experimental values of voltages around the loops:
a.
ABCEFA
Equation :
b. ABDA
Equation :
c.
CDAC
Equation :
2. Verify KCL by adding the experimental values of current at nodes :
a. A
Equation :
b. B
Equation :
c. C
Equation :
2
ii.
By Experiments
Resistor Values :
Resistor
Nominal value(ohm)
Ohmmeter reading
R1
R2
R3
R4
Table 1
Voltages :
Voltage
VAB
VBC
VAD
VDC
VBD
VAC
Theory
Experiment
% Error
Table 2
Currents :
Current
I1
I2
I3
I4
I5
Theory
Experiment
% Error
Table 3
DISCUSSION :
1.
Do the experimental and theoretical values of voltages and currents agree? Indicate the
percentage of differences.
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2.
Give possible reasons for any discrepancies.
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CONCLUSION
Give the conclusion from the experiment
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POLYTECHNIC OF KOTA BHARU
DEPARTMENT OF ELECTRICAL ENGINNERING
ET101 – ELECTRICAL TECHNOLOGY
EXPERIMENT 5
TOPIC
: VERIFICATION OF THEVENIN’S THEOREM.
OBJECTIVE
:
1.
To show the use of Thevenin’s theorem in solving problem s too complex for
Ohm’s Law
2.
To prove Thevenin’s theorem by experiment.
THEORY :
Thevenin’s theorem is an aid in simplifying complex resistive networks. It is often referred to as a
network theorem. By use of Thevenin’s theorem many sources and components can be represented
by a single resistance in series with a single voltage source. It is especially useful for simplifying
circuits with more than one power source to find the voltage drop across the load.
EQUIPMENTS:
1.
Variable power supply
2.
DC Ammeter
3.
DC Voltmeter
4.
Resistor - 1KΩ (2)
5.
Bread Board
6.
Connecting Wires
PROCEDURES :
1.
Connect the circuit of Figure 1. Leave RL out of the circuit. Calculate the VTH, RTH and the
voltage across the load in Table 1.
2.
Measure the voltage across points A and B, write down the value in Table 1.
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3.
Remove the power source connections, and rewire the circuit as shown in Figure 2.
4.
Measure the Thevenin resistance between points A and B. Write down the value in Table 1.
5.
Replace the power supply and the load resistor as seen in Figure 3. Measure the load resistor
as seen in Figure 3.
R1
R2
1k
1k
Vs
12V
RL
A
B
Figure 1
R1
R2
1k
1k
RL
A
B
Figure 2
R1
R2
1k
1k
Vs
12V
RL
500
Figure 3
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RESULTS :
The Thevenin’s Theorem for the circuit is verified. Noted the values in Table 1
Calculate VTH, RTH, VR1 and VR2
By measurement
i. Voltage across A-B, VTH
: ……………………………………….
ii. Thevenin’s resistance, RTH
: ……………………………………….
iii. Voltage across R1
: ……………………………………….
iv. Voltage across R2
: ………………………………………
v. Voltage across Load Resistor, RL
: ……………………………………..
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DISCUSSION :
Do the values obtained by your measurement match those obtained in the calculations. Explain any
differences.
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CONCLUSION
Give the conclusion from the experiment
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