EKT 212- Principles of Measurement & Instrumentation
Module 4
EKT 212
Principles of Measurement & Instrumentation
LABORATORY EXPERIMENT 4
[VOLTMETER LOADING EFFECT]
SEMESTER II (2014/2015)
NAME:
MATRIC NUMBER:
SCHOOL OF COMPUTER AND COMMUNICATION
ENGINEERING
UNIVERSITY MALAYSIA PERLIS
EKT 212- Principles of Measurement & Instrumentation
Module 4
[LOADING EFFECT MEASUREMENT]
OBJECTIVES:
1.
To determine the effect of resistive load on voltage divider circuit.
2.
To define and understand of branch current or load current.
3.
To measure voltage and current for voltage divider circuit with loaded and unloaded
effect.
EQUIPMENT/COMPONENT
Resistors
Multi-meter
Power supply
Breadboard
Jumper Wire
PROCEDURE
Part A: Voltage Divider with Resistive Load
1.
Construct a voltage divider circuit as in Figure 1. R1 = 4.7kΩ R2 = 10 kΩ
R1
4.7 k
+
10 V
_
R2
Figure 1
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10 k
Vout
EKT 212- Principles of Measurement & Instrumentation
Module 4
2.
From the circuit in Figure 1, measure the unloaded output voltage Vout. Record the
value in Table 1.
3.
Connect 10 kΩ load resistor, parallel with R2 to the circuit. Then, measure the
loaded output voltage and record the value in Table 1.
4.
Repeat Step 3 with load resistor, RL is 100 kΩ and 1.0 MΩ.
5.
From the experiment done, briefly discuss the loading effect of voltage divider
circuit. Show all your calculation.
Part B: Loading Effect of Voltmeter
1.
Construct the circuit in Figure 2 with different Ra and Rb settings that are shown at
each row as in Table 2.
2.
To measure voltage, students need to use an analog multi-meter and digital multimeter as the voltmeter.
3.
Record all the measurement in Table 2.
4.
Finally, analytically solve the circuit and calculate the voltage drop over the resistor
Rb .
Ra
+
15 V
_
+
+
Rb
V
_
-
Figure 2
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EKT 212- Principles of Measurement & Instrumentation
Module 4
RESULTS
Part A: Voltage Divider with Resistive Load
Table 1
Resistor, RL
Calculated Vb
Measured Vb
0
10 kΩ
100 kΩ
1.0 MΩ
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% Error
EKT 212- Principles of Measurement & Instrumentation
Module 4
Part B: Loading Effect of Voltmeter
Table 2
Ra
Rb
1
1 kΩ
1 kΩ
2
10 kΩ
10 kΩ
3
100kΩ
100kΩ
4
1MΩ
1MΩ
5
10MΩ
10MΩ
Calculated V2
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Measured V2
(analog MM)
Measured V2
(Digital MM)
EKT 212- Principles of Measurement & Instrumentation
Module 4
Discussion
Part A:
Discuss your findings/ results from the obtained results in Table 1.
Part B:
1. Which multimeter has higher sensitivity?
2. How can we understand that the digital multi-meter has higher internal resistance compared to the
analog multi-meter?
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EKT 212- Principles of Measurement & Instrumentation
3. Which multi-meter is more confident in terms of resistance measurement?
Conclusion
Make your overall conclusion by referring to the objective of this experiment.
-oo0oo-
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Module 4