Unit 19: Electronic Devices — Online MCQ Test
PHYSICS · NEET (All) · NEET
Practice Unit 19: Electronic Devices with a free chapter-wise online MCQ test.
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.
Unit 19: Electronic Devices — Important Questions & Answers
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.
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 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.
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.
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 :
- A. both forward bias and reverse bias
- B. increase in forward current
- C. forward bias only
- D. reverse bias only
Answer: D. reverse bias only
In reverse bias, the depletion region widens because majority carriers are pulled away from the junction.
In reverse bias, the depletion region widens because majority carriers are pulled away from the junction.