The questions along with solutions for the Electronics Discipline examination conducted by Indian Space Research Organization are as mentioned below:

ISRO 2016 Electronics

1. How does the dynamic resistance of diode vary with temperature?
a. Directly proportional
b. Inversely proportional
c. Independent
d. Directly to the square of temperature
Answer: A

2. The electric field component of a time harmonic plane EM wave traveling in a non-magnetic lossless dielectric medium has amplitude of 2 V/m. If the relative permittivity of the medium is 4, the magnitude of the time average power density vector in W/m2 is
a. 1/30π
b. 1/120π
c. 1/60π
d. 1/240π
Answer: A

3. The force on a point charge +q kept at a distance ‘d’ from the surface of an infinite grounded metal plate in a medium of permittivity ε is
a. 0
b. q2/16πεd2 away from the plate
c. q2/16πεd2towards the plate
d. q2/4πεd2 towards the plate
Answer: C

4. A material has conductivity of 10-2 mho/m and a relative permittivity of 4. The frequency at which the conduction current in the medium is equal to the displacement current is
a. 45 MHz
b. 90 MHz
c. 450 MHz
d. 900 MHz
Answer: A

5. A system has fourteen poles and two zeros. Its high frequency asymptote in its magnitude plot having a slope of
a. – 40 dB/decade
b. – 240 dB/decade
c. – 280 dB/decade
d. – 320 dB/decade
Answer: B

6. A 1mW video signal having a bandwidth of 100 MHz is transmitted to a receiver through a cable that has 40 dB loss. If the effective one sided noise spectral density at the receiver is 10-20 Watt/Hz, then the signal to noise ratio at the receiver is
a. 50 dB
b. 30 dB
c. 40 dB
d. 60 dB
Answer: A

7. When the 8051 is reset and the line is HIGH, the program counter points to the first program instruction in the
a. Internal code memory
b. External code memory
c. Internal data memory
d. External data memory
Answer: A

8. How is the status of the carry, auxiliary carry and parity flag affected after executing instructions?
MOV A, #9CH
ADD A, #64H
a. CY = 0, AC = 0, P = 0
b. CY = 1, AC = 1, P = 0
c. CY = 0, AC = 1, P = 0
d. CY = 1, AC = 1, P = 1
Answer: B

9. In the given combinational logic, X is given by
Answer: A

10. Each transistor in Darlington pair (as shown in Fig) has hfe = 100. Overall hfe of composite transistor neglecting leakage current is,
a. 10000
b. 10001
c. 10100
d. 10200
Answer: C

11. In a given network shown in figure, a steady state is reached with switch ‘k’ open. At t=0, which is closed. Determine the values of I1, I2 and I3 at t = 0+ (in Amperes).
a. 1, 1/3, 0
b. 1/3, 1/3, 1/3
c. 0, 0, 0
d. 1, 1, 1
Answer: A

12. Simplify Boolean function represented in sum of products of min-terms, F(x,y,z) = ∑m(0,2,4,5,6)
Answer: A

13. A system is described by the transfer function H(s) = 1/(S3 + αS2 + kS + 3) is stable. The constraints on α and k are
a. α > 0, αk < 3
b. α > 0, αk > 3
c. α > 0, αk > 0
d. α > 0, αk < 0
Answer: B

14. Consider a unity feedback system whose open loop transfer function is G(s) = k/s(s2 + 2s +2). The Nyquist plot for this system is
Answer: B

15. Eye diagram gives an idea of
a. Modulation scheme
b. Clock jitter
c. SNR
d. All of the above
Answer: D

16. The signal flow diagram for a certain feedback control system is shown in figure.
Now consider the following set of equations for the nodes.
1. x2 = a1x1 + 19x3
2. x3 = a2x2 + a8x4
3. x4 = a3x3 + a5x2
4. x5 = a4x4 + a6x2
Which of the following are correct?
a. 1, 2 and 3
b. 1, 3 and 4
c. 2, 3 and 4
d. 1, 2 and 4
Answer: D

17. The appropriate output frequency of 555 oscillator for RA = RB = 2.2 kΩ and C = 2000 pF
a. 110 kHz
b. 109.3 kHz
c. 120.5 kHz
d. 108.9 kHz
Answer: B

18. A counter is designed using J-K flip flop as shown in figure.
Define its count sequence
a. 000, 001, 010, 011, 100 & repeats
b. 100, 011, 010, 001, 000 & repeats
c. 010, 011, 100, 000, 001 & repeats
d. 101, 110, 111, 000, 001, 010, 011, 100 & repeats
Answer: B

19. A 1 MHz clock signal is applied to a J-K flip flop with J=K=1. What is the frequency of the flip flop output signal?
a. 2 MHz
b. 500 kHz
c. 250 kHz
d. 500 MHz
Answer: B

20. How many inputs and outputs does a full adder have?
a. 3,2
b. 2,3
c. 3,3
d. 2,2
Answer: A