physics MCQs - 12th class Chapter 05 Mcqs

1

The process of converting alternating current (AC) into direct current (DC) is called?

A

Amplification

B

Rectification

C

Oscillation

D

Modulation

2

How many diodes are used in a full-wave bridge rectifier?

A

One

B

Two

C

Three

D

Four

3

A semiconductor diode is a device that allows current to flow in how many directions?

A

One

B

Two

C

Three

D

Four

4

The p-n junction of a diode, when forward biased, offers a path of?

A

High resistance

B

Low resistance

C

Infinite resistance

D

Zero resistance

5

What is the ripple factor for a full-wave rectifier?

A

1.21

B

0.48

C

0.81

D

1.00

6

A transistor has how many terminals?

A

One

B

Two

C

Three

D

Four

7

The three terminals of a bipolar junction transistor (BJT) are Emitter, Base, and ?

A

Collector

B

Source

C

Drain

D

Gate

8

In a common-emitter (CE) amplifier, the output voltage is taken across the?

A

Emitter resistor

B

Base resistor

C

Collector resistor

D

Power supply

9

What is the phase difference between the input and output signals of a CE amplifier?

A

0°

B

90°

C

180°

D

270°

10

The current gain of a transistor in a common-emitter configuration is denoted by?

A

α

B

β

C

γ

D

δ

11

An operational amplifier (Op-Amp) has how many inputs?

A

One

B

Two

C

Three

D

Four

12

The two inputs of an Op-Amp are named inverting and ?

A

Non-inverting

B

Common

C

Differential

D

Summing

13

For an ideal Op-Amp, the input resistance is considered to be?

A

Zero

B

Low

C

High

D

Infinite

14

An Op-Amp can be used as a comparator to compare the voltage level of its?

A

Two inputs

B

Output and input

C

Power supplies

D

Internal stages

15

A light-dependent resistor (LDR) is a transducer that converts light energy into?

A

A voltage signal

B

A current signal

C

A resistance change

D

A magnetic field

16

What does LED stand for?

A

Light Emitting Diode

B

Low Energy Display

C

Light Emitting Device

D

Laser Emitting Diode

17

A photodiode is used for?

A

Generating light

B

Detecting light

C

Amplifying current

D

Regulating voltage

18

The forward bias voltage for a typical silicon diode is approximately?

A

0.3 V

B

0.5 V

C

0.7 V

D

1.0 V

19

The depletion region of a p-n junction consists of?

A

Free electrons

B

Holes

C

Mobile charge carriers

D

Immobile ions

20

The base of a transistor is typically doped?

A

Heavily

B

Moderately

C

Lightly

D

Not doped

21

An amplifier's gain is defined as the ratio of?

A

Input voltage to output voltage

B

Output voltage to input voltage

C

Input current to output current

D

Output power to input power

22

When an Op-Amp is used as an inverting amplifier, the input signal is applied to which terminal?

A

Inverting terminal

B

Non-inverting terminal

C

Output terminal

D

Ground

23

The open-loop gain of a typical Op-Amp is very?

A

Low

B

High

C

Stable

D

Unpredictable

24

Which device is designed to operate in the reverse breakdown region?

A

LED

B

Photodiode

C

Zener diode

D

Varactor diode

25

Rectification is the process of eliminating which part of the AC signal?

A

Positive half-cycles

B

Negative half-cycles

C

Either the positive or negative half-cycles

D

Both half-cycles

26

The efficiency of a half-wave rectifier is approximately?

A

40.6%

B

81.2%

C

50%

D

100%

27

A transistor can be used as a?

A

Rectifier

B

Switch

C

Resistor

D

Capacitor

28

In a pnp transistor, the majority charge carriers in the emitter are?

A

Electrons

B

Holes

C

Ions

D

Both electrons and holes

29

The collector of a transistor is doped?

A

Lightly

B

Moderately

C

Heavily

D

Same as emitter

30

An Op-Amp used as a non-inverting amplifier has a voltage gain that is always?

A

Less than 1

B

Equal to 1

C

Greater than or equal to 1

D

Negative

31

What is the function of a capacitor in a rectifier circuit?

A

To block DC

B

To filter AC ripples

C

To amplify the signal

D

To provide feedback

32

A logic gate is a digital circuit that performs a?

A

Mathematical calculation

B

Storage function

C

Logical operation

D

Switching operation

33

The output of an OR gate is HIGH if?

A

All inputs are HIGH

B

Any input is HIGH

C

All inputs are LOW

D

Any input is LOW

34

Which logic gate is known as an inverter?

A

AND gate

B

OR gate

C

NOT gate

D

XOR gate

35

The output of a NAND gate is LOW only when?

A

All inputs are LOW

B

Any input is LOW

C

All inputs are HIGH

D

Any input is HIGH

36

A NOR gate is a combination of which two gates?

A

NOT and AND

B

NOT and OR

C

NAND and OR

D

XOR and NOT

37

The boolean expression for an AND gate with inputs A and B is?

A

A + B

B

A . B

C

A'

D

A XOR B

38

How many basic logic gates are there?

A

Two

B

Three

C

Four

D

Five

39

The process of obtaining a smooth DC output from a rectifier is called?

A

Amplification

B

Modulation

C

Filtration

D

Regulation

40

A Zener diode is commonly used for?

A

Voltage regulation

B

Amplification

C

Rectification

D

Oscillation

41

In an npn transistor, the arrow on the emitter symbol points?

A

Inward

B

Outward

C

Towards the base

D

Towards the collector

42

The gain of an inverting amplifier is given by the ratio of?

A

-Rf / Ri

B

1 + (Rf / Ri)

C

Ri / Rf

D

Rf

43

A device that can turn ON or OFF in response to a small input signal is acting as a?

A

Filter

B

Switch

C

Oscillator

D

Rectifier

44

A stable DC voltage is provided by a?

A

Rectifier circuit

B

Voltage regulator

C

Filter circuit

D

Transformer

45

The binary number system uses how many digits?

A

1

B

2

C

8

D

10

46

The output of an XOR gate is HIGH if the inputs are?

A

The same

B

Different

C

Both HIGH

D

Both LOW

47

A full-wave rectifier is more efficient than a half-wave rectifier because it utilizes?

A

One half-cycle

B

Both half-cycles

C

A transistor

D

A larger capacitor

48

In forward biasing a p-n junction, the positive terminal of the battery is connected to the?

A

n-type material

B

p-type material

C

Depletion region

D

Barrier potential

49

The purpose of the base region in a transistor is to?

A

Emit charge carriers

B

Collect charge carriers

C

Control the flow of charge carriers

D

Provide structural support

50

The resistance of an LDR is low when?

A

It is in the dark

B

It is exposed to light

C

It is reverse biased

D

It is heated