NTA UGC NET/JRF Exam, December-2019 (Electronic Science)

Total Questions: 100

81. Important elements of sampling circuit of sampling oscilloscope are given below

(a) Voltage comparator
(b) Blocking oscillator
(c) Staircase generator
(d) Ramp generator
The correct sequence of the above elements in the sampling circuit in the direction from trigger input to horizontal signal is:

Correct Answer: D. (b), (d), (a), (c)

82. In 8051, Program Status Word (PSW) is 8- bit flag register having following status flag bits:

(a) AC
(b) RS1
(c) CY
(d) OV
Arrange these in ascending order of bit position in PSW register:

Correct Answer: A. (d), (b), (a), (c)

83. Consider the following logic families:

(a) MOS
(b) TTL
(c) RTL
(d) ECL
Rearrange these logic families according to their propagation delay in descending order:

Correct Answer: C. (a), (c), (b), (d)

84. Four sources are generating information as given below:

Arrange these sources in the descending order of their entropy (H)

Correct Answer: B. (a), (d), (c), (b)

85. Arrange the following materials in order of increasing mobility of holes (at 300 K)

(a) C
(b) Ge
(c) SiC
(d) GaAs
The correct sequence is:

Correct Answer: B. (c), (d), (a), (b)

86. Given below are two statements. One is labelled as Assertion (A) and the other is labelled as reason (R):

Assertion (A): Gain margin is the factor by which the system gain can be decreased to drive it to the verge of instability.
Reason (R): Gain margin is the reciprocal at the gain at frequency at which the phase angle becomes 180°.
Choose the correct option:

Correct Answer: D. (A) is false, but (R) is true

87. Given below are two statements. One is labelled as Assertion (A) and the other is labelled as reason (R):

Assertion (A): Optical fibers have higher bandwidth as compared to conventional copper cables.
Reason (R): The information carrying capacity of optical fiber is limited by Rayleigh scattering loss.
Choose the correct option:

Correct Answer: B. Both (A) and (R) are true and (R) is not the correct explanation of (A)

88. Given below are two statements. One is labelled as Assertion (A) and the other is labelled as reason (R):

Assertion (A): The process of testing the frequency response of amplifier and filters can be done by sweep frequency generator that automatically varies its frequency over a pre-determined range.
Reason (R): The sweep frequency generator should have a ramp generator which applies a linear ramp voltage to the input of a voltage tuned oscillator (VTО).
Choose the correct option:

Correct Answer: A. Both (A) and (R) are true and (R) is the correct explanation of (A)

89. Given below are two statements. One is labelled as Assertion (A) and the other is labelled as reason (R):

Assertion (A): Clocked R-S flipflops are considered semi-transparent.
Reason (R): The output Q of a clocked R-S flipflop changes state in response to input changes immediately provided ENABLE is high.
Choose the correct option:

Correct Answer: A. Both (A) and (R) are true and (R) is the correct explanation of (A)

90. Given below are two statements. One is labelled as Assertion (A) and other is labelled as reason (R):

Assertion (A): The bipolar junction transistor is designed to get large β.
Reason (R): During fabrication, the base width is kept small.
Choose the correct option:

Correct Answer: A. Both (A) and (R) are true and (R) is the correct explanation of (A)