Chapter Exam

Unit 19: Electronic Devices — Online MCQ Test

Q: The solids which have the negative temperature coefficient of resistance are:

Answer: C. insulators and semiconductors — Both insulators and semiconductors exhibit a decrease in resistance (or an increase in conductivity) with an increase in temperature, resulting in a negative temperature coefficient of resistance.

Q: For the logic circuit shown, the truth table is:

Answer: A. A 0 0 1 1; B 0 1 0 1; Y 1 1 1 0 — The circuit consists of two NOT gates feeding into a NOR gate. Y = NOT(NOT A OR NOT B) = A AND B is not correct. The gates are NOT gates followed by a NOR gate. Y = NOT(NOT A OR NOT B) which is equivalent to A AND B? No, Y = NOT(NOT(A) OR NOT(B)) = A AND B. Wait, looking at symbol, it is a NOR gate (OR with circle). Output Y = NOT(NOT A OR NOT B) = A AND B? No, De Morgan's: NOT(NOT A OR NOT B) = A AND B. Actually, the NOR gate with inverted inputs is an AND gate.

Q: The output (Y) of the given logic implementation is similar to the output of an/a _______gate.

Answer: D. NOR — Determined by logic gate truth table reduction.

Q: A full wave rectifier circuit with diodes (D1) and (D2) is shown in the figure. If input supply voltage Vin = 220sin(100πt) volt, then at t = 15 m sec

Answer: B. D1 is reverse biased, D2 is forward biased — At t = 15ms, phase = 100π * 0.015 = 1.5π radians = 270 degrees. sin(270) = -1. For the standard configuration, this negative peak biases D2 forward.

Q: The increase in the width of the depletion region in a p-n junction diode is due to :

Answer: D. reverse bias only — In reverse bias, the depletion region widens because majority carriers are pulled away from the junction.

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Practice Unit 19: Electronic Devices with a free chapter-wise online MCQ test for NEET NEET (All) PHYSICS. This chapter covers: Semiconductors; semiconductor diode: I-V characteristics in forward and reverse bias; diode as a rectifier; I-V characteristics of LED. the photodiode solar cell and Zener diode; Z.... AI-generated questions from basic to board-exam level, with instant results and explanations.

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Unit 19: Electronic Devices — Important Questions & Answers (FAQ)

Frequently asked questions from NEET NEET (All) PHYSICS — Unit 19: Electronic Devices, with answers and explanations. These are sample questions; the exam has its own separate question set.

The solids which have the negative temperature coefficient of resistance are:

A. insulators only
B. semiconductors only
C. insulators and semiconductors ✓
D. metals

Answer: C. insulators and semiconductors
Both insulators and semiconductors exhibit a decrease in resistance (or an increase in conductivity) with an increase in temperature, resulting in a negative temperature coefficient of resistance.

For the logic circuit shown, the truth table is:

A. A 0 0 1 1; B 0 1 0 1; Y 1 1 1 0 ✓
B. A 0 0 1 1; B 0 1 0 1; Y 0 1 1 1
C. A 0 0 1 1; B 0 1 0 1; Y 1 0 0 0
D. A 0 0 1 1; B 0 1 0 1; Y 0 0 0 1

Answer: A. A 0 0 1 1; B 0 1 0 1; Y 1 1 1 0
The circuit consists of two NOT gates feeding into a NOR gate. Y = NOT(NOT A OR NOT B) = A AND B is not correct. The gates are NOT gates followed by a NOR gate. Y = NOT(NOT A OR NOT B) which is equivalent to A AND B? No, Y = NOT(NOT(A) OR NOT(B)) = A AND B. Wait, looking at symbol, it is a NOR gate (OR with circle). Output Y = NOT(NOT A OR NOT B) = A AND B? No, De Morgan's: NOT(NOT A OR NOT B) = A AND B. Actually, the NOR gate with inverted inputs is an AND gate.

The output (Y) of the given logic implementation is similar to the output of an/a _______gate.

A. AND
B. NAND
C. OR
D. NOR ✓

Answer: D. NOR
Determined by logic gate truth table reduction.

A full wave rectifier circuit with diodes (D1) and (D2) is shown in the figure. If input supply voltage Vin = 220sin(100πt) volt, then at t = 15 m sec

A. D1 is forward biased, D2 is reverse biased
B. D1 is reverse biased, D2 is forward biased ✓
C. D1 and D2 both are forward biased
D. D1 and D2 both are reverse biased

Answer: B. D1 is reverse biased, D2 is forward biased
At t = 15ms, phase = 100π * 0.015 = 1.5π radians = 270 degrees. sin(270) = -1. For the standard configuration, this negative peak biases D2 forward.

The increase in the width of the depletion region in a p-n junction diode is due to :