CUET-UG SERIES

Physics

Semiconductor Electronics Materials Devices And Simple Circuits

6 previous year questions.

Volume: 6 Ques

Yield: Medium

High-Yield Trend

1

2025

4

2023

1

2022

Chapter Questions
6 MCQs

01

PYQ 2022

medium

physics ID: cuet-ug-

Choose the logic operation carried out by the following current:

1

OR

2

AND

3

NAND

4

NOR

02

PYQ 2023

hard

physics ID: cuet-ug-

Match List I with List II List I List II (A) Zener Diode (II) Voltage Regulator (B) LED (III) Remote Control (C) Rectifier (IV) AC to DC (D) Photo diode (I) Detect optical signal

1

A-I, B-II, C-III, D-IV

2

A-II, B-IV, C-I, D-III

3

A-III, B-II, C-IV, D-I

4

A-II, B-III, C-IV, D-I

03

PYQ 2023

medium

physics ID: cuet-ug-

Which of the following statements are correct? (A) The resistivity of a semiconductor decreases with increasing temperature. (B) The potentiometer is unaffected by the internal resistance of the source. (C) In ionic crystals and electrolytic liquids electrons carry the electric current. (D) Ohm's law fails if V depends on I non-linearly. (E) Kirchhoff's rules are used for analysis of electric circuits. Choose the correct answer from the options given below:

1

(B), (C) and (E) only

2

(A), (B), (D) and (E) only

3

(C), (D) and (E) only

4

(A), (C) and (D) only

04

PYQ 2023

medium

physics ID: cuet-ug-

A semiconductor has an electron concentration of 8 x 10 13 m -3 and hole concentration of 2 \times 10 3 m -3 . The semiconductor behaves as:

1

n-type semiconductor

2

p-type semiconductor

3

intrinsic semiconductor

4

p-n junction

05

PYQ 2023

medium

physics ID: cuet-ug-

The forbidden energy band gap in conductors, semi conductors and insulators are E G1, E G2 and E G3, respectively. The relation among them is

1

E G1 >E G2 > E G3

2

E G1 G2 G3

3

E G1 =E G2 =E G3

4

E G1 < E G2 > E G3

06

PYQ 2025

medium

physics ID: cuet-ug-

Below given are some statements about electronic devices: (A) Diodes can be used for rectifying an ac voltage. (B) For semiconductors, band gap energy E > 3 eV. (C) By changing the external applied voltage, junction barriers can be changed. (D) p-n junction is the 'key' to all semiconductor devices. Choose the correct answer from the options given below:

1

(A), (B) and (D) only

2

(A), (B) and (C) only

3

(B), (C) and (D) only

4

(A), (C) and (D) only

Official Solution

Correct Option: (4)

Step 1: Understanding the Concept: This question tests fundamental knowledge about semiconductors and p-n junction diodes. We need to evaluate each statement's validity. Step 2: Detailed Explanation: (A) Diodes can be used for rectifying an ac voltage. A diode allows current to flow easily in one direction (forward bias) and offers very high resistance in the opposite direction (reverse bias). This unidirectional property is exactly what is needed to convert alternating current (AC) into direct current (DC), a process called rectification. This statement is correct . (B) For semiconductors, band gap energy E > 3 eV. Materials are classified based on their band gap energy (). For semiconductors, the band gap is relatively small, typically in the range of 0.2 eV to 3 eV (e.g., Silicon eV, Germanium eV). Materials with a band gap eV are generally classified as insulators (e.g., Diamond eV). Therefore, this statement is incorrect . (C) By changing the external applied voltage, junction barriers can be changed. A p-n junction has a potential barrier (or depletion region). Applying an external voltage (biasing) alters this barrier. A forward bias voltage reduces the barrier height, allowing current to flow. A reverse bias voltage increases the barrier height, blocking current flow. Thus, the junction barrier can be controlled by an external voltage. This statement is correct . (D) p-n junction is the 'key' to all semiconductor devices. The p-n junction is the fundamental building block for a vast majority of semiconductor devices, including diodes, transistors (which can be seen as two back-to-back p-n junctions), solar cells, LEDs, etc. Its ability to control current flow is central to modern electronics. This statement is generally considered correct in the context of introductory electronics. Step 3: Final Answer: Statements (A), (C), and (D) are correct, while (B) is incorrect. The correct option is (D).