# Potentiometer MCQ

1. A potentiometer can not be used to

1. Measure emf of a cell
2. Compare emf of two cells
3. Measure unknown temperature
4. Measure the internal resistance of a cell
Answer
Answer. d

2. For measuring an A.C. voltage by an A.C. potentiometer the supply for the potentiometer is taken from

1. Same source as unknown voltage
2. Different source other than unknown voltage
3. A battery
4. Source of supply does not matter
Answer
Answer. a

3. A standard cell of 1.0185 V is used with a slide wire potentiometer. The balance was obtained at 60 cm. When an unknown emf was connected, the balance was obtained at 82 cm. What is the magnitude of unknown emf?

1. 1.39 V
2. 0.75 V
3. 13.9 V
4. 7.45 V
Answer
Answer. a

4. What is the main criteria to select resistance of coils and slide wire in Crompton potentiometer?

1. 14 coils and slide wire all having the same resistance
2. 14 coils and slide wire but the resistance of slide wire is half of that of each coil
3. 14 coils and slide wire all having the different resistance
4. 14 coils out of which 7 coils have resistance which is twice that of the remaining 7 coils
Answer
Answer. a

5. What is the main purpose of the potentiometer as a device for?

1. Comparing two voltages
2. Comparing two currents
3. Measuring a voltage
4. Measuring a current
Answer
Answer. a

6. During the measurement of a low resistance using a potentiometer, the following readings were obtained:

Voltage drop across unknown resistance = 0.531 volt.

Voltage drop across a 0.1 ohm standard resistance connected in series with the unknown = 1.083 Volt. Value of the unknown resistor is

1. 49.03 miliohm
2. 108.3 milliohm
3. 20.4 miliohm
4. 53.1 miliohm
Answer
Answer. a

7. A potentiometer is used to measure the voltage between two points of a D.C. circuit, which is found to be 1.2 V. This is also measured by a voltmeter, which is found to be 0.9 V. The resistance of the voltmeter is 60 kΩ. The input resistance between two points.

1. 60 kΩ
2. 20 kΩ
3. 45 kΩ
4. 80 kΩ
Answer
Answer. b

8. Current in a circuit is measured using a simple slide wire. What will be the voltage drop per unit length if the standard cell is of emf 2.38 V balanced at length of 35 cm?

1. 0.68 V/cm
2. 0.068 V/cm
3. 68 V/cm
4. 6.8 V/cm
Answer
Answer. b

9. The standardization of AC potentiometer is done by using

1. d.c. standard sources and transfer instruments
2. a.c. standard voltage source directly
3. a.c. standard sources and transfer instrument
4. d.c. standard sources and d.c. galvanometer
Answer
Answer. c

10. Standardization of potentiometer is done in order that, they become

1. Accurate
2. Precise
3. Accurate and direct reading
4. Accurate and precise
Answer
Answer. c

11. A potential divider is normally connected

1. Outside the generator circuit towards the load circuit
2. Within the generator circuit
3. At a distance V/100 meters from the generator where V is the voltage to be measured in kV
4. None of these
Answer
Answer. a

12. Which type of potentiometer consists of two separate potentiometer circuits enclosed in a common case?

1. Gall tinsley AC potentiometer
2. Drysdale tinsley AC potentiometer
3. Cambell Larsen potentiometer
4. Cromton potentiometer
Answer
Answer. a

13. Find the maximum value of excitation voltage for potentiometer, if there is a power dissipation of 6 W and maximum value resistance of the potentiometer is 500 Ω.

1. 300 V
2. 3000 V
3. 54.77 V
4. 90 V
Answer
Answer. c