Electronic Instruments MCQ|Objective Questions on Electronic Instruments

1. Digital instruments are those which

(a) have numerical readout

(b) use LED or LCD displays

(c) have a circuitry of digital design

(d) use deflectioin type meter movement.

2. The main difference between the electronic and electrical  instruments is that an electronic instrument contains

(a) an electronic device (b) a transducer

(c) a digital readout (d) electrons.

3. The essential elements of an electronic instrument

are

(a) transducer (b) signal conditioner

(c) indicating device (d) all of the above.

4. The current sensitivity of a meter is expressed in

(a) ampere (b) ohm/ampere

(c) ohm/volt (d) ampere/division.

5. The basic meter movement can be converted

into an ohmmeter by connecting a …..with it.

(a) high resistance in series

(b) low resistance in parallel

(c) battery in series

(d) battery and a variable resistance in series

6. The D’ Arsonval meter movement can be converted

into an audio-frequency ac ammeter by

adding a …… to it.

(a) thermocouple (b) rectifier

(c) chopper (d) transducer.

7. In a linear meter, half-scale deflection occurs

when there is … per cent of the rated current

through its coil

(a) 100 (b) 25

(c) 50 (d) 75

8. A 0-1 mA meter has a sensitivity of

(a) 1 k Ù/V (b) 1 mA

(c) 1 k Ù (d) 1000 A.

9. A moving coil instrument has a resistance of 10 Ù

and takes 40 mA to produce full-scale deflection.

The shunt resistance required to convert this instrument

for use as an ammeter of range 0 to 2 A

is

(a) 0.1021 Ù (b) 0.2041 Ù

(c) 0.2561 Ù (d) 0.4210 Ù

10. A moving coil ammeter has a fixed shunt of 0.02

ohm resistance. If the coil resistance of the meter

is 1000 Ù, a potential difference of 500 mV is required

across it for full-scale deflection. Under

this condition, the current in the shunt would be

(a) 2.5 A (b) 25 A

(c) 0.25 A (d) 0.025 A

11. It is desired to convert a 0-1000 μA meter movement,

with an internal resistance of 100 Ù into

a 0-100 mA meter. The required value of shunt

resistance is about

(a) 1 Ù (b) 10 Ù

(c) 99 Ù (d) 100 Ù

12. Loading effect is principally caused by… instruments

(a) high resistance (b) low-sensitivity

(c) high-sensitivity (d) high-range

13. A multimeter is used to measure

(a) resistance (b) current

(c) voltage (d) all of the above

14. A sinusoidal voltage of rms value 10 V is applied

to a D’ Arsonval movement connected in series

with a half-wave rectifier. It will show a reading

of… volt

(a) 9 (b) 4.5

(c) 10 (d) 7.7

15. A VTVM produces negligible loading effect on

a circuit under test primarily because

(a) it virtually drawn no current from the circuit

(b) of its very high internal resistance

(c) it uses high vacuum tubes

(d) it is a null deflection instrument.

16. In a 3½ digit voltmeter, the largest number that

can be read is

(a) 0999 (b) 1999

(c) 4999 (d) 9999

17. A 3½ digit voltmeter having a resolution of 100

mV can be used to measure maximum voltage of

(a) 100 V (b) 200 V

(c) 1000 V (d) 5000 V

18. The signal to be observed on the screen of an

oscilloscope is applied

(a) across its X-plates (b) across its Y -plates

(c) to the horizontal amplifier

(d) to the trigger circuit.

19. When a 30 V dc is applied to the vertical deflection

plates of a cathode ray tube, the bright

spot moves 1 cm away from the centre. If 30 V

(rms) ac is applied, then the movement of the

spot will be nearly

(a) 1 cm (b) 1.5 cm

(c) 2 cm (d) 3 cm

20. Production of a steady stationary display of a

signal waveform on the scope screen is due to

(a) persistence of vision

(b) flourescent material of the screen

(c) proper sync. between the signal and the

sweep generator

(d) electrostatic focussing of the electron beam.

21. Two sinusoidal signals of frequency f and 3f are

applied at x and y inputs respectively to an oscilloscope.

Which one of the following patterns

can be observed on the screen ?

(a) (b)

(c) (d)

22. The X– and Y -inputs of a CRO are respectively

V sin wt and −V sin wt. The resulting Lissajous

pattern will be

(a) a straight line (b) a circle

(c) an elipse (d) a figure of eight

23. The deflection sensitivity of a CRT depends inversely

on the

(a) length of the vertical deflecting plates

(b) distance between screen and deflecting plates

(c) deflecting voltage

(d) separation between Y -plates.

24. Two complete signal cycles would be displayed

on the screen of a scope when time-period of

the sweep generator is …… the signal time period.

(a) half (b) twice

(c) equal (d) thrice

25. A non-triggered oscilloscope is one which

(a) has no sweep generator

(b) cannot produce a stable stationary screen

display

(c) has a continuously running time-base genera

tor

(d) can display a portion of the input signal

wave form.

26. A dual-trace CRO has

(a) one electron gun (b) two electron guns

(c) one electron gun and one two-pole switch

(d) two electron guns and one two-pole switch

27. The operation a Q-meter is based on

(a) self-induction (b) series resonance

(c) mutual induction (d) eddy currents.

28. The resolution of a logic analyser is

(a) maximum number of input channels

(b) the minimum duration of the glitch it can

capture

(c) its internal clock period

(d) the minimum amplitude of the input signal

it can display

29. A spectrum analyser can be described as

(a) voltage selective frequency meter

(b) current selective frequency meter

(c) frequency selective voltmeter

(d) None of these

1. (c) 2. (a) 3. (d) 4. (c) 5. (d) 6. (b) 7. (c) 8. (a) 9. (b) 10. (b)

11. (a) 12. (b) 13. (d) 14. (b) 15. (b) 16. (a) 17. (c) 18. (a) 19. (a) 20. (c)

21. (b) 22. (a) 23. (d) 24. (b) 25. (c) 26. (c) 27. (b) 28. (a) 29. (d)

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