Latest Electronics Objective Questions
1. Which one of the following is most suitable for measuring very small capacitances?
(a) Transformer ratio-arm bridge
(b) Schering bridge
(c) Wien’s bridge
(d) De-Saute bridge
Ans:-B
2. Which of the following are the requirements of a CRO (cathode ray oscilloscope) for display of high frequency signals (megahertz)?
1. Input capacitance should be low.
2. Cathode ray tube should be provided with post-acceleration.
3. Shrot persistence phosphors should be used in the screen.
4. Electromagnetic focussing and deflection system should be used
Select the correct answer using the codes given below:
Codes:
(a) l, 2 and 4
(b) l, 3 and 4
(c) 1, 2 and 3
(d) 2, 3 and 4
Ans:-D
3. The controlling torque and the electromagnetic damping of the flux meter are
(a) small and heavy respectively
(b) heavy and small respectively
(c) both heavy
(d) both small
Ans:-A
4. If an induction type energy meter runs fast, it can be slowed down by adjusting the
(a) lag
(b) light load
(c) position of braking magnet and making it move closer to the centre of the disc
(d) position of braking magnet and making it move away from the centre of the disc
Ans:-A
5. In the measurement of strain by Wheatstone bridge, the maximum sensitivity is obtained by a combination of
(a) an active and dummy strain gauges
(b) two active and two dummy strain gauges
(c) three active and one dummy strain gauges
(d) four active strain gauges
Ans:-C
6. In a digital voltmeter, ‘over-ranging’ implies switching
(a) OFF (1/2) digit
(b) ON (1/2) digit
(c) ON next 4 digits
(d) ON an indicator.
Ans:-B
7. Which of the following units are needed for designing a data acquisition system using 8085 microprocessor?
1. An AID converter
2. A DIA converter
3. A programmable peripheral device
4. A timer
Select the correct answer by using the codes given below:
Codes:
(a) l and 4
(b) 3 and 4
(c) l and 3
(d) 2 and 4
Ans:-C
Directions: The following questions consist of two statements, one labelled the “Assertion A” and the other labelled the ‘Reason R’. You are to examine these two statements carefully and decide f the Assertion A and the Reason R are individually true and f so, whether the Reason is a correct explanation of the Assertion. Select your answers to these items using the codes given below and mark your answer sheet accordingly.
Codes:
(a) Both A and R are true and R is the correct explanation of A
(b) both A and R are true but R Is NOT a correct explanation of A
(c) A is true but R is false
(d) A is false but R is true
8. Assertion (A): By superimposing the log magnitude versus phase angle plot of open-loop transfer function on Nichols chart, it is possible to determine the closed-loop frequency response of the system.
Reason (R): Nichols chart gives constant M and N loci in the gain-phase plane.
Ans:-A
9. Assertion (A): A communication satellite is a microwave link repeater.
Reason (R): A communication satellite receives the signal beamed up by an earth station. It amplifies this signal and retransmits it to ground station.
Ans:-B
10. Assertion (A): FM systems exhibit threshold.
Reason (R): Noise affects the instantaneous frequency in a non-linear fashion.
Ans:-B
11. The mean square value of the shot noise current
(a) Varies inversely as average current
(b) is independent of average current
(c) Varies as ?average current
(d) Varies directly as average current
Ans:- D
12. Consider the following features regarding satellite communication:
1. Height of Satellite
2: Downlink frequency
3. Gain of transmitting antenna
4. Gain of receiving antenna
The free space transmission loss depends on
(a) 1 and 3
(b) l and 2
(c) 2 and 3
(d) 3 and 4
Ans:-B
13. In a Mesh topology of communication network, if there are N stations, the total number of possible full duplex links is
(a) N—1
(b) N (N—1)
(c) N (N—1) / 2
(d) (N-1) / 2
Ans:-D
14. Values of VSWR measured by terminating the load end of a transmission line first with horn, then with a short and finally with a matched load, will be respectively
(a) 20, 1.9 and 1.01
(c) 1.9, 1.01 and 20
(b) 20, 1.01 and 1.9
(a) 1.9, 2O and 1.01
Ans:-D
15. In an 8085 microprocessor, the accumulator contents get altered by the instruction
(a) ANI 5C
(b) CMP C
(c) CPI 3A
(d) ORA A
Ans:- D
16. The maximum value of mutual Inductance of two inductively coupled coils with self inductance L1 = 49 mH and L 2 = 81 mH is
(a) 130 mH
(b) 63 mH
(c) 32 mH
(d) 3969 mH
Ans:-B
17 . The resonant frequency of a series RLC circuit is 1.5 MHz with the resonating capacitor set at l50 pF. If the bandwidth is 10 kHz, then the effective resistance of the circuit in Ohms would be approximately
(a) 29.5
(b) 14.75
(c) 9.4
(d) 4.7
Ans:-B
18. The system y (t) = tx (t) + 4 is
(a) Non-linear, time-varying and unstable
(b) Linear, time-varying and unstable
(c) Non-linear, time-invariant and unstable
(d) Non-linear, time-varying and stable
Ans:-A
19. A signal of bandwidth 4 kHz is recorded in a tape recorder at normal speed. If for transmission purposes, the recorder is replayed at 4 times the normal speed, then the transmission bandwidth will be
(a) 16 kHz
(b) 8 kHz
(c) 4 kHz
(d) 1 kHz
Ans:-A
20. In LED, light is emitted because
(a) Recombination of charge carriers takes place
(b) Diode gets heated up
(c) Light falling on the diode gets amplified
(d) Light gets reflected due to lens action
Ans:-A
21. The gain of a negative feedback amplifier is 40 dB. If the attenuation of the feedback path is 50 dB, then the gain of the amplifier without feedback is
(a) 78.92
(b) 146.32
(c) 215.51
(d) 317.23
Ans:-B
22. The following table provides a comparison of the performances of common base (CB), common emitter (CE) and common collector (CC) configurations of a transistor:
Parameter CB CE CC
1. Input impedance low medium high
2. Current gain high low high
3. Voltage gain >1 >1 <1
In this table, the performances of CB, CE and CC have been correctly indicated in respect of parameters
(a) 1, 2 and 3
(b) 1 and 2
(c) 2 and 3
(d) l and 3
Ans:-C
23. Which one of the following statements is NOT correct?
(a) If everything else is equal, then a 10 bit digital ramp ADC. will have a better resolution but a longer conversion time than an 8 bit ADC
(b) The conversion time for a successive approximation increase with the increase in input voltage
(c) A flash ADC does not contain a DAC
(d) VCO is the main component of a voltage to frequency ADC
Ans:-B
24. A full adder circuit may be constructed by using
(a) two 2-input AND gates and two 3-input. OR gates
(b) two half address and a 2-input AND gate
(c) two half address and a 2-input OR gate
(d) two 2-input AND gates and two 3-input XOR gates
Ans:-C
25. If (211) x = (152) g , then the value of base ‘x’ is
(a) 3
(b) 5
(c) 7
(d) 9
Ans:-C