Download Experiment 5 - Portal UniMAP

UNIVERSITI MALAYSIA PERLIS
ELECTRICAL ENGINEERING TECHNOLOGY
EMT 113/4
EXPERIMENT 5
d’ARSONVAL GALVANOMETER
MARKS
Result
Calculation
Discussion
Conclusion
Total
%
5
20
5
5
35
100
NAME
PROGRAMME
MATRIK #
GROUP
DATE
d’Arsonval Galvanometer
EMT113/4
EXPERIMENT 5
TITLE : d’ARSONVAL GALVANOMETER
OBJECTIVES
1.
To find the internal resistance and the current sensitivity of the galvanometer.
EQUIPMENTS
d’Arsonval Galvanometer kit (mA), digital multimeter and connecting wires.
INTRODUCTION
The galvanometer contains a coil of wire in a magnetic field, which will
experience a torque when a current passes through the wire of the coil. The coil
is attached to a pointer and a spring so that the amount of deflection of the
pointer is proportional to the current in the wire of the coil.
The value of the load resistor (R1) will be set to a specified value and the
potential difference provided by the power supply will be varied to obtain a fullscale deflection of the pointer of the galvanometer. The voltage (VFS) required to
obtain full-scale deflection will be recorded, without changing the applied voltage
(VFS), Add a shunt resistor (RS) in parallel with the galvanometer. Vary the load
resistance to get the full-scale deflection in the galvanometer. The new load
resistance, R2 will be recorded. In both circuits, the potential difference supplied
by the power supply is the same as is the current passing through the
galvanometer (full-scale deflection in both circuits).
Application of Kirchhoff’s rules to the two circuits results in the following
expression for the value of the internal resistance of the galvanometer (Rg).
Rg = [ RS ( R1-R2 ) ] / R2
The current sensitivity (K) can be obtained form the measurement by using this
formula
K = VFS / [ N( R1+R2 ) ]
where, N = number of major divisions of the galvanometer scale for a full-scale
deflection of the pointer
R1 = load resistor in circuit 1
R2 = load resistor in circuit 2
RS = value of shunt resistor parallel to galvanometer
VFS = voltage at full-scale deflection of the pointer in galvanometer
PUSAT PENGAJIAN KEJURUTERAAN MIKROELEKTRONIK
1
d’Arsonval Galvanometer
EMT113/4
PROCEDURE
1. Adjust the pointer scale of galvanometer of the d’Arsonval galvanometer trainer
kit exactly to 0.
2. Set the resistance box, R1 to 2.2 kΩ. Keep the voltage knob in minimum position,
0V. Connect the circuit as in the Figure 5-1 below.
Figure 5-1 Set up of circuit connection
3. Turn ON the supply, The galvanometer pointer will deflect towards right hand
side or left hand side. Next, vary the 0-5V potential knob until the galvanometer
shows its maximum deflection, which the pointer should comes to 30 positions
(divisions).
4. Now, connect the digital multimeter across the 0-5V terminal to measure the
voltage and record this value. This voltage is called as VFS.
5. Turn OFF the supply and do not disturb the voltage knob. Now connect the
resistance, RS and construct the circuit as in Figure 5-2 below. Select the 10 Ω
for RS. Note that, now R1 is change to R2. Switch ON the instrument, then the
pointer of the galvanometer will return back by a few divisions.
Figure 5-2 The circuit diagram with shunt resistor, RS
6. Next, do not disturb the voltage knob.Adjust the resistance box, R2 until the
pointer scale comes to full scale deflection which is 30 positions (divisions).
Observe the pointer of the galvanometer.
PUSAT PENGAJIAN KEJURUTERAAN MIKROELEKTRONIK
2
EMT113/4
d’Arsonval Galvanometer
7. Turn OFF the supply and disconnect R2. Measure the absolute values of R2
using multimeter and record the value in the table.
8. Finally disconnect the galvanometer from the circuit and connect multimeter
across the terminal of galvanometer to measure its internal resistance. Record
the value as Rg.
9. The values of VFS, R1, R2, RS, and Rg are known, so determine the galvanometer
resistance, Rg by calculation. Then calculate its current sensitivity, K.
10. Repeat from step 5 with Rs = 5Ω and Rs = 2Ω. Record all the measured values.
11. Next, change the value of R1 to 1.2kΩ for Rs = 10Ω , 5Ω and 2Ω respectively.
Repeat from step 2.
12. Calculate the Mean of calculated Rg and Mean of K.
13. Calculate the percentage error of Rg.
Note: Record all value for R2 which is measured from multimeter only.
PUSAT PENGAJIAN KEJURUTERAAN MIKROELEKTRONIK
3
EMT113/4
d’Arsonval Galvanometer
RESULT
PUSAT PENGAJIAN KEJURUTERAAN MIKROELEKTRONIK
4
EMT113/4
d’Arsonval Galvanometer
CALCULATION
PUSAT PENGAJIAN KEJURUTERAAN MIKROELEKTRONIK
5
EMT113/4
PUSAT PENGAJIAN KEJURUTERAAN MIKROELEKTRONIK
d’Arsonval Galvanometer
6
OP-AMP SINEWAVE 'NON-INVERT'
d’Arsonval Galvanometer
output voltage input
EMT113/4
DISCUSSION
Based on the experiments, discussed your measurement and theoretical result.
time
CONCLUSION
Based on your measurement data, make your overall conclusion by referring to the
objective of this experiment. (your answer should be in simple notes).
PUSAT PENGAJIAN KEJURUTERAAN MIKROELEKTRONIK
7