NTA UGC NET/JRF Exam, February-2023 (Electronic Science)

Total Questions: 100

61. Inverters are having following properties:

(a) VSI uses force commutation
(b) VSI has negligible impedance
(c) VSI has large source impedances
(d) They work like choppers
Choose the correct answer from the options given below:

A. (b) and (d) only
B. (a), (c) and (d) only
C. (a) and (b) only
D. (a) and (d) only

Correct Answer: C. (a) and (b) only

Solution:

Voltage Source Inverters (VSIs) are a type of inverter that provide a constant voltage output from a variable voltage input.

(a) True. VSIs typically employ force commutation, especially when working with devices that don't have inherent commutation.

(b) Generally, VSI's are designed to have negligible impedance to avoid significant voltage drops.

Inverters play a pivotal role in converting DC to AC, particularly in contexts such as renewable energy systems where energy stored in batteries needs conversion to supply to the grid.

62. The value of Kp in Proportional, PI, PID, controllers are given

(a) For proportional Kp = T/L
(b) For PI, Kₚ = 0.9 T/L
(c) For PI, Kₚ = 1.7 T/L
(d) For PID, Kₚ = 1.2 T/L
(e) For PID, Kₚ = 0.9 T/L
Choose the correct answer from the options given below:

A. (a), (b) and (d) only
B. (a), (b) and (e) only
C. (a) and (e) only
D. (c) and (d) only

Correct Answer: A. (a), (b) and (d) only

Solution:

The value of Kₚ, the proportional gain, in different controllers helps in adjusting the control system's response.

(a) For a simple proportional controller, Kₚ might be given by T/L, where T and L are constants associated with the system dynamics.

(b) In a Proportional-Integral (PI) controller, the Kₚ may often be slightly modified to account for the integral action. The given value suggests Kₚ = 0.9 T/L.

(d) PID controllers, incorporating proportional, integral, and derivative actions, might have another value for Kₚ. Here, Kₚ = 1.2 T/L is given.

Tuning these constants appropriately ensures optimal performance of control systems in various applications, from industrial systems to home appliances.

63. Incorrect statements regarding measurement are given:

(a) Hot wire anemometer is used to measure displacement
(b) Hall effect is used to measure current
(c) LVDT is used to measure acceleration and gas flow
(d) Piezoelectric Transducer is used to measure acceleration
Choose the correct answer from the options given below:

Correct Answer: (e) (*)

Solution:

Either question or options is wrong.

64. Consider the following statements associated with electrical and electronic transducers

(a) Little power is consumed by transducer
(b) Mass intertia effects are not minimized
(c) The response time is small
(d) Transmission and processing the signal for the purpose of measurement are easier.
Choose the correct answer from the options given below:

A. (a), (b) and (d) only
B. (a), (c) and (d) only
C. (a), (b) and (c) only
D. (b), (c) and (d) only

Correct Answer: B. (a), (c) and (d) only

Solution:

Electrical and electronic transducers are fundamental in transforming one form of energy into another, often converting a physical quantity into an electrical signal.

(a) True. Most transducers are designed to consume minimal power, especially sensors in battery-powered devices.

(c) In many applications, a quick response time of the transducer is crucial. For instance, in real-time monitoring systems, delays could be detrimental.

(d) With advancements in technology, the processing and transmission of signals have become increasingly efficient and easier.

The realm of transducers has been pivotal in enabling innovations from touchscreens to advanced monitoring systems in industries.

65. Consider the following statements regarding the advantages of Anderson Bridge

(a) It is the modification of the Maxwell's inductance Capacitance Bridge
(b) For measuring the low Q of coils, it is not superior to Maxwell's bridge
(c) It is not simple as compared to Maxwell's Bridge
(d) It can be used to determine mutual inductance
Choose the correct answer from the options given below:

A. (a), (b) and (d) only
B. (b), (c) and (d) only
C. (a), (c) and (d) only
D. (a), (b) and (c) only

Correct Answer: C. (a), (c) and (d) only

Solution:

Anderson Bridge is a modified form of Maxwell's bridge and is used to measure the inductance of a coil.

(a) True. It's a development over the Maxwell's inductance-capacitance bridge, primarily used for the measurement of selfinductance.

(d) Although primarily designed for selfinductance, under specific configurations, it can measure mutual inductance as well.

Such bridges are essential tools in laboratories and industries, allowing for precise measurements and calibrations.

66. Match List-I with List-II.

List-I	List-II
(a) Porcelain	I. Used for high frequency applications
(b) Steatite	II. Releases water when heated
(c) Mica	III. Used for capacitors to be operated in high frequency cases.
(d) Rutile	IV. Used for insulators.

Choose the correct answer from the options given below:

	(a)	(b)	(c)	(d)
A.	IV	I	III	II
B.	IV	II	III	I
C.	II	I	III	IV
D.	III	II	IV	I

Correct Answer: B.

Solution:

List-I matches with List-II as:

(a) Porcelain - IV. Used for insulators. Porcelain, with its excellent insulating properties, is commonly used for hightension electrical insulators.

(b) Steatite - II. Releases water when heated. Steatite is a ceramic material, which, when heated, can release the water bound in its structure.

(c) Mica - III. Used for capacitors to be operated in high-frequency cases. Mica has excellent dielectric strength and is resistant to high temperatures, making it ideal for capacitors especially in highfrequency applications.

(d) Rutile - I. Used for high-frequency applications.

Rutile is a form of titanium dioxide and is used in various high-frequency electronic applications, including as a dielectric in some electronic components.

67. Match List-I with List-II.

List-I	List-II
$(a)$ When negative $V_G$ is applied to gate of MOS	I. Depletion
$(b)$ When zero-bias is applied to gate of MOS	II. Surface Inversion
$(c)$ When a small positive gate bias $V_G$ is applied to gate of MOS	III. Accumulation
$(d)$ When a higher positive gate $V_G$ is applied to gate of MOS	IV. Neutral MOS

Choose the correct answer from the options given below:

	(a)	(b)	(c)	(d)
A.	II	III	I	IV
B.	IV	III	II	I
C.	I	IV	III	II
D.	II	I	IV	III

Correct Answer: (E) (*)

Solution:

Either question or options is wrong.

68. Match List-I with List-II.

List-I	List-II
$(a)$ Power	I. dBi
$(b)$ Gain	II. Watts
$(c)$ Resistance	III. Henry
$(d)$ Inductance	IV. Ohm

Choose the correct answer from the options given below:

	(a)	(b)	(c)	(d)
A.	I	III	II	IV
B.	IV	III	I	II
C.	III	I	IV	II
D.	II	I	IV	III

Correct Answer: D.

Solution:

List-I matches with List-II as:
(a) Power - II. Watts.
Power is measured in Watts (W) in the
International System of Units.
(b) Gain - I. dBi.
Gain, especially in the context of antennas, is often measured in decibels referenced to an isotropic antenna (dBi).
(c) Resistance - IV. Ohm.
The unit of electrical resistance is the ohm (Ω).
(d) Inductance - III. Henry.
Inductance is measured in henrys (H) in the International System of Units.

69. Match List-I with List-II.

Choose the correct answer from the options given below:

	(a)	(b)	(c)	(d)
A.	II	I	IV	III
B.	I	II	IV	III
C.	II	I	III	IV
D.	III	IV	II	I

Correct Answer: B.

70. Match List-I with List-II.

Choose the correct answer from the options given below:

	(a)	(b)	(c)	(d)
A.	I	III	IV	II
B.	II	I	III	IV
C.	IV	I	II	III
D.	II	III	IV	I

Correct Answer: C.

Solution:

List-I matches with List-II as:
(a) NOT GATE - IV. A logical gate that inverts its input.
(b) AND GATE - I. Logical multiplication. Only gives a high output (1) when both its two inputs are high.
(c) OR GATE - II. Logical addition. Gives a high output (1) if one or both of its inputs are high.
(d) EX-OR Gate - III. Gives a high output (1) when its two inputs are different.
In the realm of digital electronics, these gates form the building blocks of complex digital circuits, making them integral to modern electronics and computing.