## ELECTRONIC INSTRUMENTS Questions with Answers :-

1. An ammeter is connected in …………….. with the circuit element whose current we wish to measure

1. Series
2. Parallel
3. Series or parallel
4. None of the above
Ans : 1

2. A galvanometer in series with a high resistance is called ……………

1. An ammeter
2. A voltmeter
3. A wattmeter
4. None of the above
Ans : 2

3. An ammeter should have ………….. resistance

1. Infinite
2. Very large
3. Very low
4. None of the above
Ans : 3

4. A voltmeter is connected in a ………….. with the circuit component across which potential difference is to be measured

1. Parallel
2. Series
3. Series or parallel
4. None of the above
Ans : 1

5. A voltmeter should have ………. resistance

1. Zero
2. Very high
3. Very low
4. None of the above
Ans : 2

6. The sensitivity of a multimeter is given in ……………..

O
Amperes
kO/V
none of the above
Ans : 3

7. If the full-scale deflection current of a multimeter is 50 µA, its sensitivity is ……..

10 kO/V
100 kO/V
50 kO/V
20 kO/V
Ans : 4

8. If a multimeter has a sensitivity of 1000 O per volt and reads 50 V full scale, its internal resistance is ………..

20 kO
50 kO
10 kO
None of the above
Ans : 2

9. A VTVM has ………. input resistance than that of a multimeter

More
Less
Same
None of the above
Ans : 1

10. The input resistance of a VTVM is about ………..

1000 O
10 kO
20 kO
10 MO
Ans : 4

11. If the negative potential on the control grid of CRT is increased, the intensity of spot ………….

Is increased
Is decreased
Remains the same
None of the above
Ans : 2

12. For display of signal pattern ………… voltage is applied to the horizontal plates of a CRO

Sinusoidal
Rectangular
Sawtooth
None of the above
Ans : 3

13. Two multimeters A and B have sensitivities of 10 kO/V and 30 kO/V respectively. Then …………..

Multimeter A is more sensitive
Multimeter B is more sensitive
Both are equally sensitive
None of the above
Ans : 2

14. A galvanometer of resistance G is shunted by a very small resistance S. The resistance of the resulting ammeter is ………………

GS/(G+S)
G+S
G-S
None of the above
Ans : 1

15. A VTVM is never used to measure …………..

Voltage
Current
Resistance
None of the above
Ans : 2

16. The sensitivity of a voltmeter which uses a 100 µA meter movement is ……………..

1 kO/V
10 kO/V
5 kO/V
Data insufficient
Ans : 2

17. What is the total resistance of a voltmeter on the 10 V range when the meter movement is rated for 50 µA of full-scale current?

10 kO
20 kO
200 kO
None of the above
Ans : 3

18. The materil used to coat inside the face of CRT is …………..

Carbon
Sulphur
Silicon
Phosphorous
Ans : 4

19. When an ammeter is inserted in the circuit, the circuit current will ………..

Increase
Decrease
Remain the same
None of the above
Ans : 2

20. A series ohmmeter circuit uses a 3 V battery and a 1 mA meter movement. What is the half-scale resistance for this movement?

3 kO
kO
kO
6 kO
Ans : 1

21. The most accurate device for measuring voltage is ………….

Voltmeter
Multimeter
CRO
VTVM
Ans : 3

22. The horizontal plates of a CRO are supplied with …………. to observe the waveform of signal.

Sinusoidal wave
Cosine wave
Sawtooth wave
None of the above
Ans : 3

23. A CRO is used to measure ………….

Voltage
Frequency
Phase
All of above
Ans : 4

24. If 2% of the main current is to be passed through a galvanometer of resistance G, then resistance of the shunt required is ……….

G/50
G/49
49 G
50 G
Ans : 2

25. Which of the following is likely to have the largest resistance?

Voltmeter of range 10 V
Moving coil galvanometer
Ammeter of range 1 A
A copper wire of length 1 m and diameter 3 mm
Ans : 1

26. An ideal ammeter has ………… resistance

Low
Infinite
Zero
High
Ans : 3

27. The resistance of an ideal voltmeter is …………

Low
Infinite
Zero
High
Ans : 2

28. To send 10% of the main current through a moving coil galvanometer of resistance 99 O the shunt required is …………..

11 O
9 O
100 O
9 O
Ans : 1

29. A voltmeter has a resistance of G ohms and range V volts. The value of resistance required in series to convert it into voltmeter of range nV is ……………

nG
G/n
G/(n-1)
(n-1)G
Ans : 4

30. An ammeter has a resistance of G ohms and range of I amperes. The value of resistance required in parallel to convert it into an ammeter of range nI is ………….

nG
(n-1)G
G/(n-1)
G/n
Ans : 3