Question Bank on Electrical, Electronics Instrumentation 2019

Question Bank on Electrical, Electronics Instrumentation 2019.

1. In order for a 30 volt, 90 watt lamp to work properly in a 120 volt supply the required series resister in ohm is

(A) 10 (B) 20
(C) 30 (D) 40

2. According to Theremin’s theorem, any linear active network can be replaced by a single voltage source

(A) in series with a single impedance
(B) in parallel with a single impedance
(C) in series with two impedances
(D) in parallel with two impedances

3. The internal resistance of ammeter is

(A) very small (B) very high
(C) infinite (D) zero

4. Hay bridge is used mainly for the measurement of

(A) resistance (B) inductance
(C) conductance (D) capacitance

5. Which of the following is true about series resonance

(A) The reactance becomes zero and impedance becomes equal to resistance
(B) The current in the circuit becomes maximum
(C) The voltage drop across inductance and capacitance cancels each other
(D) All of the above statements are correct

6. A 3-Ф, 4 wire, 400/230 v feeder supplies 3-phase motor and an unbalanced lighting load. In this system

(A) all four wires will carry equal current
(B) neutral wire will carry no current
(C) neutral wire will carry both motor current and lighting load current
(D) neutral wire will carry current only when lighting load is switched on

7. Equalizing connections are required when paralleling two

(A) alternators
(B) compound generators
(C) series generators
(D) both (B) and (C)

8. An ideal transformer is one which

(A) has a common core for its primary and secondary windings
(B) has no losses and magnetic leakage
(C) has core of stainless steel and windings of pure copper metal
(D) has interleaved primary and secondary windings

9. The principle of operation of a 3-phase induction motor is most similar to that of a

(A) synchronous motor
(B) repulsion-start induction motor
(C) transformer with a shorted secondary
(D) capacitor-start, induction-run motor

10. In the forward region of its characteristic, a diode appears as

(A) an OFF switch
(B) a high resistance
(C) a capacitor
(D) an ON switch

11. The common-emitter forward amplification factor βdc is given by

(A) IC/IE (B) IC/Ib
(C) IE/IC (D) IB/IF

12. A common emitter amplifier is characterized by

(A) low voltage gain
(B) moderate power gain
(C) signal phase reversal
(D) very high output impedance

13. After VDS reaches pinch-off value VP in a JFET, drain current IO becomes

(A) zero (B) low
(C) saturated (D) reversed

14. An electronic oscillator

(A) needs an external input
(B) provides its own input
(C) is nothing but an amplifier
(D) is just a dc/ac converter

15. In an SCR, the function of the gate is to

(A) switch it off
(B) control its firing
(C) make it unidirectional
(D) reduce forward breakdown voltage

16. NAND and NOR gates are called ‘universal’ gates primarily because they

(A) are available everywhere
(B) are widely used in IC packages
(C) can be combined to produce AND, OR and NOT gates
(D) are the easiest to manufacture

17. Registers and counters are similar in the sense that they both

(A) count pulses
(B) store binary information
(C) are made from an array of flip-flops and gates integrated on a single chip
(D) are in fact shift register

18. A flip-flop

(A) is a sequential logic device
(B) is a combinational logic device
(C) remembers what was previously stored in it
(D) both (A) and (C)

19. An operational amplifier

(A) can be used to sum two or more signals
(B) can be used to subtract two or more signals
(C) uses to principle of feed back
(D) all of the above

20. TTL logic is preferred to DRL logic because

(A) greater fan-out is possible
(B) greater logic levels are possible
(C) greater fan-in is possible
(D) less power consumption is possible

An electron rising through a potential of 250 V will acquire an energy of :

(A) 250 eV

(B) 800 eV

(C) 250 J

(D) 800 J

If the amount of impurity, either donor type or acceptor type added to the intrinsic

semiconductor is controlled to 1 part in one million, the conductivity of the sample :

(A) increases by a factor 103

(B) reduces by a factor 10−3

(C) increases by a factor 106

(D) reduces by a factor 10−6

4. Laplace transform and Fourier integrals are related through :

(A) frequency domain

(B) time domain

(C) both frequency and time domain

(D) none

A clamper circuit :

(i) adds or subtracts a dc voltage to or from a waveform

(ii) does not change the shape of the waveform

(iii) amplifies the waveform

(A) (i) and (ii) are correct

(B) (i) and (iii) are correct

(C) (ii) and (iii) are correct

(D) (i), (ii) and (iii) are correct

A ring counter consisting of five flip flop will have :

(A) 5 states

(B) 10 states

(C) 32 states

(D) infinite states

Which one of the following can be used as parallel to series converter ?

(A) Decoder

(B) Encoder

(C) Digital counter

(D) Multiplexer

An interrupt in which the external device supplies its address as well as the interrupt

request, is known as :

(A) vectored interrupt

(B) maskable interrupt

(C) polled interrupt

(D) non-maskable interrupt

An instruction that can be recognized and used without translation must be written

in :

(A) Source code

(B) Machine code

(C) Basic language

(D) Assembly code

The angle for which there is no reflection and the incident wave is vertically polarized

is known as :

(A) Steradian angle

(B) Reflection angle

(C) Brewster’s angle

(D) Critical angle

A PLL can be used to demodulate :

(A) PAM signals

(B) PCM signals

(C) PM signals

(D) DSB-SC signals

The main function of balanced modulator is to :

(A) produce balanced modulation of a carrier wave

(B) produce 100 percent modulation

(C) suppress carrier signal in order to create a single side band or double side band

(D) limit noise picked up a receiver

An SCR can be termed as :

(A) DC switch

(B) AC switch

(C) Both DC and AC switch

(D) Square wave switch

Fiber optics communication offers the largest bandwidth in the range of :

(A) 1010 Hz

(B) 106 Hz

(C) 1014 Hz

(D) 1020 Hz

Silicon photosensors have their maximum spectral response in the :

(A) infrared region

(B) ultraviolet region

(C) visible region

(D) X-ray region

See Also……