# ELECTRONIC INSTRUMENTS

## ELECTRONIC INSTRUMENTS Questions and 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
Infinite

Very large
Very low
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
Parallel
Series
Series or parallel
None of the above
Ans : 1
5. A voltmeter should have ………. resistance
Zero
Very high
Very low
None of the above
Ans : 2
6. The sensitivity of a multimeter is given in ……………..
OA
mperes
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 