NTA UGC NET/JRF Exam, September-2022 (Electronic Science)

Total Questions: 100

21. Which one of the following is not the feature of 8051?

Correct Answer: C. 16 Interrupts

22. In a version of 8051 the crystal frequency is 12 MHz, find the time delay associated with loop section of the followign DELAY subroutine. Consider the machine cycle lasts 12 clock cycles of the crystal frequency:

DELAY: MOV R3, # 200
HERE: NOP
NOP
NOP
DJNZ R3; HERE
RET

Correct Answer: B. 1 milli second

23. D

CLR A
MOV R1, # 100H
MOV R7, # 21H
AGAIN: MOV @ R1, A
INC R1
DJNC R7, AGAIN

Correct Answer: C. Clears 33 RAM locations starting from address 100 H D. Clears 33

24. A stepper motor has the following specifications:

Step angle: 2°
Steps per revolution: 180
Number of rotor teeth: 45
Movement per 4 - step sequence: 8°
The following program will rotate a motor by how many degrees?

Correct Answer: A. 64°

25. The absolute potential at a point P which is 2 m from a point charge of +5µC is given by:

Correct Answer: A. 22.5 kV

26. A sphere of radius r₁ = 30 cm has a charge density variation Po(r/r1) where P₀ = 200 pC/m³. The value of total charge on the sphere is:

Correct Answer: A. 17 pC

27. To match the impedance of a 'ground penetrating radar antenna' to the ground, impedance of ground is given by the expression, (if ∈ᵣ= 14, µᵣ = 1, o = 10⁻² Um, operating frequency = 200 MHz):

Correct Answer: A.

28. For an isotropic antenna Pₙ(θ, φ) = 1, D = 1, for all θ and φ . The beam area for the isotropic antenna is given by:

Correct Answer: В. 4π

29. The appropriate value of modulation index ẞ for transition between narrow band and wide band FM is considered

Correct Answer: В. 0.471

30. For a given probability of error, binary coherent FSK is inferior to binary coherent PSK by:

Correct Answer: C. 3 dB