Home/Physics Mcqs/Physics Electronics Online Mcqs Test

Physics Electronics Online Mcqs Test

Malik TahirLast Updated: October 13, 2025

Important Electronics Question and Answer

Total Questions:	177
Time Allowed:	60 Minutes
Total Marks:	177
How to Attempt Test:	Please choose the right Option in MCQ-type question.
Test Helpful For:	Physics Test ECAT Test MDCAT Test FPSC/PPSC/SPSC/KPPSC/BPSC/AJKPSC/NTS Physics Interview Question Answer

Physics Electronics Practice Test Online With Explanation

Please wait...

1. Photovoltaic cell produces electrical energy from

Heat energy

None of these

Light energy

Chemical energy

2. The potential difference across the depletion region of silicon is

0.7 V

0.5 V

0.9 V

0.67 V

3. The width of a depletion layer in a p-n junction is

Increased by forward biasing

Decreased by reverse biasing

Is independent of voltage

Increased by reverse biasing

4. Light emitting diode work when it is

Reverse biased

Forward biases

Both

None of these

5. In junction diode, the holes are because of:

Missing electrons

Neutrons

Extra electrons

Protons

6. Non-inverting amplifier circuits have

A very low input impedance

A low output impedance

A very high input impedance

None of these

7. Which logic gate is represented by following diagram?

EOR

AND

NOR

8. Semi-conductors with donor atoms and free electrons belong to the type

mix

any of above

9. Which is normal used of transistor?

Diode

P-type material

Rectifier

Switching device

10. A substance which have empty conduction band is called

None of these

Semiconductor

Insulator

Conductor

11. A diode as a rectifier converts:

High voltage to low voltage

D.C. into A.C.

Low voltage to high voltage

A.C. into D.C.

12. A pieced of copper and another of germanium are cooled from room temperature to 77 K, the resistance of

Each of them increases

Each of them decreases

Copper increases and germanium decreases

Copper decreases and germanium increases

13. LDR means:

Light dependent resistance

Low degree resistor

Low degree radiations

None of these

14. When a pentavalent material like As, is added to tetravalent material l.e. Ge, we get a

Semiconductor

Super conductor

P-type material

N-type material

15. A junction between p-type material and n-type material is called as

Transistor

Diode

Rectifier

Amplifier

16. The part of a transistor which is most heavily doped to produce large number of majority carriers is

Emitter

Collector

Can be any of the above three

Base

17. In Germanium crystal, impurity donor elements have valiancy

18. The logic gate that will have HIGH or “1” at its output when any one of its input if HIGH is a(n):

OR gate

NOR gate

AND gate

NOT gate

19. The impurity atoms with which a pure silicon should be doped to make a p-type semiconductor is

Aluminum

Antimony

Phosphorus

Arsenic

20. In semiconductors at a room temperature

The valence band is completely filled

The valence band is completely filled and the conduction band is partially filled

The valence band is partially empty and the conduction band is partially filled

The conduction band is completely empty

21. NAND gate is

A universal gate

Not a universal gate

A basic gate

A basic universal gate

22. When n-type of semiconductor is heated,

Number of holes increases while that of holes decreases

Number of electrons increases while that of holes decreases

Number of electrons and holes increases equally

Number of electrons and holes remains same

23. The thickness of the base is equal to

Mean of thickness of emitter and collector

Very small as compared to the thickness of emitter and collector

Thickness of collector

Thickness of emitter

24. The energy band gap is maximum in

Superconductors

Metals

Insulators

Semiconductors

25. In a n-p-n transistor:

Holes move from base to collector

Negative charge moves from emitter to base

Holes move from emitter to base

Negative charge moves from collector to base

26. The energy band gap is maximum in

Superconductors

Semiconductors

Insulators

Metals

27. On increasing the reverse bias to a large value in a p-n junction diode current

Suddenly increases

Remain fixed

Increases slowly

Decreases slowly

28. Symbol represents

NAND gate

NOT gate

NOR gate

XNOR gate

29. A non-inverting closed-loop op-amp circuit generally has a gain factor:

Less than one

Of zero

Greater than one

Equal to one

30. At absolute zero, Si acts as

Non-metal

Insulator

None of these

Metal

31. When boron is added as an impurity to silicon, the resulting material is:

p-type semiconductor

p-type conductor

n-type semiconductor

n-type conductor

32. Which of the following is not characteristic of an op—amp

It offers a very high inputs resistance to the input current

None of these

It offers a very low output resistance

It offers a very low open loop gain all of above

33. Reverse bias applied on a junction diode

Increases the majority carrier current

Raises the potential barrier

Increase the minority carrier current

Lowers the potential barrier

34. When a semiconductor is continuously heated, then value of its resistance

Increases

Remains unchanged

Decreases and then increases

Decreases

35. Electrons present in p-type material due to thermal pair generation are

Majority carriers

Minority carriers

Blockers

Dual carriers

36. In the transistor schematic symbol, the arrow

Point from north to south

Is located on the base

Is locate on the collector

Is located on the emitter

37. If on increasing temperature the resistance decreases, then it is

None of these

Insulator

Superconductor

Semiconductor

38. The positive sign of gain indicates that

None of these

Input and out signals are in phase

May be in phase or not

Input and out signals are not in phase

39. In a semiconductor, the mobility of holes is

Greater than electrons

Equal to electrons

Less than electrons

None

40. Depletion region of a junction is formed

Under forward bias

When temperature varies

Under reverse bias

During the manufacturing process

41. When a strength changes the length of a body, it is called

None of these

Tensile stress

Compress ional stress

Shear stress

42. A photodiode can turn its current ON and OFF in

Millisecond

Nanosecond

Microsecond

None of these

43. The measure of deformation of a solid when stress is applied to it is called

Force

None of these

Stress

Strain

44. Exclusive-OR (XOR) logic gates can be constructed from what other logic gates?

AND gates and NOT gates

Or gates and NOT gates

OR gates only

AND gates, OR gates, and NOT gates

45. Copper and germanium are cooled to 70 K from room temperature, then

Resistance of copper increases while that of germanium decreases

Resistance of copper decreases while that of germanium increases

Resistance of both increases

Resistance of both decreases

46. Suitable impurities are added to a semiconductor depending on its use. This is due to:

Increase its electrical resistivity

Increases its electrical conductivity

Increase its life

Enable it to Telerate higher voltage

47. In n-type substances, the minority carriers are

None of these

Holes

Electrons

Neutrons

48. In the middle of the depletion layer of a reverse-biased p-n junction, the

Potential is maximum

Potential is zero

Electric field is zero

Electric field is maximum

49. A device which converts an alternating current to direct current is called

Rectifier

P-type material

Oscillator

Amplifier

50. In p-type semi-conductor, the majority charge carriers are

Electrons

Neutrons

Holes

Protons

51. The number of junctions in the PNP transistor are

52. The semiconductor diode can be used as a rectifier because _

It has high resistance to the current flow when reverse biased

It has low resistance to the current flow when forward biased

It has low resistance to the current flow when forward biased & high resistance when reverse biased

Its conductivity increases with rise of temperature

53. p-type crystal of a p-n junction diode is connected to a positive terminal of battery and n-type crystal connected to negative terminal of battery

Diode is reverse biased

Potential barrier in depletion layer increases

Diode is forward based

Potential barrier in depletion layer remains unchanged

54. Barrier potential of a p-n junction diode does not depend on:

Temperature

Doping density

Diode design

Forward bias

55. Application of photodiode is/are

None of these

Logic gates

Automatic switching

Detection of visible and invisible radiations

56. Due to high loop gain of the amplifier, the inverting and non-inverting inputs are

Non-inverting terminal is at high potential

Both are at the high potential

Inverting terminal is at high potential

Both are at the same potential

57. In insulators

Conduction band is filled with electrons and valence band is empty

Conduction band is partially filled with electrons

Valence band is partially filled with electrons

Conduction band is empty and valence band is filled with electrons

58. The impurity atoms with which a pure silicon should be doped to make a p-type semiconductor is

Phosphorus

Antimony

Aluminum

Arsenic

59. When NPN transistor is used as an amplifier

Holes move from base to emitter

Electrons move from collector to base

Electrons move from emitter to base

Electrons move from base to emitter

60. The forward resistance of the diode is

Ohms

Many ohms

None of these

Few ohms

61. Output voltage in full wave rectification is not smooth. In order to have smooth output voltage

Capacitor is used

None of these

Solvent is used

Resistor is used

62. At room temperature, a p-type semi-conductor has

Large number of free electrons and few holes

Large number of holes and few electrons

Large number of holes and electrons

Equal number of free electrons and holes

63. Which of the following when added as an impurity into the silicon produces n-type semi-conductor?

64. Due to the break down the p-n junction suffers

Works efficiently

None of these

Damaged

Require more current

65. Two inputs of NAND gates are shorted. This gate is equivalent to

OR gate

AND gate

XOR gate

NOT gate

66. At absolute zero, Si acts as

Non-metal

None of these

Metal

Insulator

67. An OP-AMP comparator is a circuit that compares the signal voltage on one of its inputs with a _

Virtual input

Non-inverting voltage at output

Output

Reference voltage on the other

68. In Germanium crystal, impurity donor elements have valiancy

69. Suitable impurities are added to a semiconductor depending on its use. This is due to

Increase its life

Enable it to Telerate higher voltage

Increase its electrical conductivity

Increase its electrical resistivity

70. The electrical circuit used to have smooth DC output from a rectifier circuit is called

Filter

Oscillator

Logic gates

Amplifier

71. To use a transistor as an amplifier

Both junctions are reverse biased

The emitter base junction is forward biased and the base collector junction is reverse biased

Both junctions are forward biased

No bias voltages are required

72. Using OP-Amp as an inverting amplifier, the non-inverting terminal has potential

Zero

None of these

High

Low

73. When no light is incident on photodiode, the reverse current is

Very low

Zero

Very high

Almost negligible

74. When the conductivity of a semiconductor is only due, to breaking of covalent bonds, the semiconductor is called

Extrinsic

n-type

Intrinsic

p-type

75. Transistors with various combinations are widely used as switches in:

Transformers

Computers

Electric generations

Electric motors

76. In comma emitter amplifier (l₀/lE) = 0.98, then current gain is

9.8

4.9

77. The ratio of tensile stress to tensile strain is called

Young’s modulus

Modulus of electricity

Bulk’s modulus

None of these

78. To obtain a p-type germanium semiconductor, it must be doped with

Arsenic

Indium

Antimony

Phosphorus

79. The critical temperature for mercury is

7.2 K

1.18 K

3.72 K

4.2 K

80. n-type semiconductor if formed

From pure Si crystal

When a Ge crystal is doped with an impurity containing 3 valence electrons

When a Ge crystal is doped with an impurity containing 5 valence electrons

From pure Ge crystal

81. The working of transistor as amplifier is similar to

Step up transformer

Step down transformer

Triode vacuum tube

Three diodes in common

82. A device for converting an alternating current into a pulsating from or direct current is known as

Rectifier

Oscillator

Detector

None of these

83. In common emitter amplifier (l₀/lE) = 0.98, then current gain is

4.9

9.8

84. In the middle of the depletion layer of a reverse-biased p-n junction, the

Potential is zero

Electric field is zero

Electric field is maximum

Potential is maximum

85. Semi-conductor germanium and silicon are

Trivalent

Tetravalent

Pentavalent

Divalent

86. Young’s modulus for copper is

110 Nm¯²

91 x 10 Nm¯²

None of these

70 x 10 Nm¯²

87. The part of a transistor which is most heavily doped to produce large number of majority carriers is

Base

Can be any of the above three

Emitter

Collector

88. p-n junction when reversed biased acts as a

Capacitor

On switch

Off switch

Inductor

89. Transistor can be used as

Filter

Half wave rectifier

Full wave rectifier

Amplifier

90. The least doped region in a transistor is

Collector

Either emitter or collector

Base

Emitter

91. The p-n junction diode works as insulator, if connected

In reverse bias

To A.C.

In forward bias

None of these

92. When a semiconductor is continuously heated, then value of its resistance

Remains unchanged

Decreases and then increases

Decreases

Increases

93. In junction diode, the holes are because of:

Protons

Extra electrons

Neutrons

Missing electrons

94. When n-p-n transistor is used as an amplifier

Electrons move from base to collector

Holes move from emitter to base

Holes move from emitter be base

Holes move from base to emitter

95. The switch is open when the resistance between C and E becomes

None of these

Almost zero

Zero

Infinity

96. Zener breakdown in a semiconductor diode occurs when

Forward current exceeds certain value

Forward bias exceeds certain value

Reverse bias exceeds certain value

Potential barrier is reduced to zero

97. When n-p-n transistor is used as an amplifier,

Holes move from emitter to base

Electrons move from base to collector

Holes move from base to emitter

98. When arsenic is added as an impurity to silicon, the resulting material is

None of these

N-type conductor

P-type semiconductor

N-type semiconductor

99. A piece of copper and another of germanium are cooled from room temperature to 77 K, the resistance of

Each of them decreases

Copper increases and germanium decreases

Copper decreases and germanium increases

Each of them increases

100. In a p-type semiconductor germanium is doped with:

All of above

Aluminum

Gallium

Boron

101. The energy gap between conduction band and valence band is order 0.07 eV. It is a

Semiconductor

Conductor

Alloy

Insulator

102. Identify the correct statement about minority carriers

Holes in n-type and p-type

Free electrons in n-type and holes in p-type

Holes in n-type and free electrons in p-type

Free electrons in n-type and p-type

103. In the p-type semi-conductor the majority and minority charge carriers are respectively

Electrons and protons

Holes and electrons

Protons and electrons

Electrons and holes

104. The electrons in the outermost shell of an atom are called

Free electrons

None of these

Valence electrons

Tightly bound electrons

105. In a n-p-n transistor:

Holes move from emitter to base

Holes move from base to collector

Negative charge moves from emitter to base

Negative charge moves from collector to base

106. A signal applied at the non-inverting input, of an O.P that appears after amplification at the output terminal, with

90° Phase shift

120° Phase shift

No Phase shift

180° Phase shift

107. Acceptor and donor impurities donate

n-carriers only

p-carriers only

p-carriers and n-carriers respectively

n-carriers and p-carriers respectively

108. The materials in which valence band and conduction band overlap are called

Superconductors

Insulators

Semiconductors

Conductors

109. If positive end of battery is connected to p-side and negative end of battery is connected to n-side of diode then

None of these

Diode is reverse biased

Diode is forward biased

Diode is neutralized

110. A n-p-n transistor conducts when

Collector is positive and emitter is negative with respect to the base

Collector is positive and emitter is at negative potential as the base

Both collector and emitter are negative with respect to the base

Both collector and emitter are positive with respect to the base

111. In a PN junction

High potential at N side and low potential at P side

P and N both are at same potential

Undetermined

High potential at P side and low potential at N side

112. The least doped region in a transistor is

Collector

Base

Emitter

113. The ratio β represents

114. A diode as a rectifier converts:

D.C. into A.C.

A.C. into D.C.

High voltage to low voltage

Low voltage to high voltage

115. The width of a depletion layer in a p-n junction is

Decreased by reverse biasing

Increased by reverse biasing

Is independent of voltage

Increased by forward biasing

116. In semiconductors at a room temperature

The valence band is partially empty and the conduction band is partially filled

The valence band is completely filled and the conduction band is partially filled

The conduction band is completely empty

The valence band is completely filled

117. In forward bias, the width of potential barrier in a p-n junction diode

Decreases

Remains constant

First A and B

Increases

118. A transistor consists of

Two PN-junctions

One PN-junction

Four PN-junctions

Three PN-junctions

119. An OP-AMPs can amplify

A.C.

None of these

D.C.

Both A.C. & D.C.

120. The operation of a transistor requires

None of these

That the base be heated

That the collector be heated

That the emitter be heated

121. Diode can work as

Rectifier

Oscillator

Modulator

Multivibrator

122. In a p-type semiconductor germanium is doped with:

Boron

All of these

Aluminum

Gallium

123. In reverse biasing of p-n junction, the resistance offered by the diode is of the order of

Kilo ohms

Ohms

Mega ohms

Several mega ohms

124. n-type germanium is obtained on doping intrinsic germanium with

Aluminum

Boron

Gold

Phosphorus

125. A p-n junction has a thickness of the order of:

10¯¹² cm

10¯⁶ cm

1 cm

1 mm

126. Conversion of low input a.c. into high output a.c. is called:

All of these

Amplification

Magnification

Rectification

127. When an alternating accelerating field is applied to a charge it produces

Electromagnetic Waves

Gamma Rays

x-rays

Transverse Waves

128. Arsenic, antimony or phosphorus are impurities of

may be p-type or n-type

n-type

None of these

p-type

129. In forward bias the width of potential barrier

Decreases

No effect

Remains same

Increases

130. Which one is reverse-biased?

131. When a p-n junction diode is reverse biased, the flow of current across the junction is mainly due to

Diffusion of charges

Depends upon the nature of material

Drift of charges

Both drift and diffusion of charges

132. The output will be a LOW for any case when one or more inputs are zero in a(n):

OR gate

AND gate

NAND gate

NOT gate

133. In n-p-n transistor, p works as

Collector

Base

Emitter

Any of above

134. The transistor provide good power amplification when they are used in

Common base configuration

Common collector configuration

Common emitter configuration

None of these

135. The part of a transistor, which is heavily doped to produce a large number of majority carriers, is

Collector

None of these

Emitter

Base

136. In insulators

Valence band is partially filled with electrons

Conduction band is empty and valence band is filled with electrons

Conduction band is filled with electrons and valence bad is empty

Conduction band is partially filled with electrons

137. In p – n junction, after diffusion, a charge less region is formed around the junction is called

None of these

Charged region

Diffusion region

Depletion region

138. When the conductivity of a semiconductor is only due to breaking of covalent bonds, the semiconductor is called

p-type

Extrinsic

Intrinsic

n-type

139. The gain A of the amplifier is of the order of

Hundreds

Man hundred

None of these

Thousands

140. Reverse bias applied on a junction diode

Increases the majority carrier current

Lowers the potential barrier

Raises the potential barrier

Increase the minority carrier current

141. The electromagnetic waves emitted by the LC circuit of areal to a transmitting station are of

Zero amplitude

Constant amplitude

Unit amplitude

Variable amplitude

142. When we apply reverse bias to a junction diode, it

Lowers the potential barrier

Raises the potential barrier

Increase the minority carrier current

Increase the majority carrier current

143. When the output of OR gate is 1

Only if both inputs are 1

If either or both inputs are 1

If either input is zero

If both inputs are zero

144. In a junction diode, the holes are due to

Missing of electrons

Neutrons

Extra electrons

Protons

145. When aluminum is added as an impurity to silicon, then resulting material is

n-type semiconductor

n-type conductor

p-type conductor

p-type semiconductor

146. Polythene, potystrene and nylon are examples of

Amorphous solids

Polymeric solids

Glassy solids

Crystalline solids

147. In between two consecutive permissible energy bands, there is a range of energy states which cannot be occupied by electrons. These are called

Forbidden energy states

None of these

Hidden energy states

Band levels

148. The especially designed semiconductor diodes used as indicator lamps in electronic circuits are

The photo diodes

The switch

Solar cells

The light emitting diode

149. A single transistor can be used to build which of the following digital logic gates?

OR gates

NAND gates

AND gates

NOT gates

150. The electrical circuit used to bet smooth DC output from a rectifier circuit is called

Logic gates

Oscillator

Amplifier

Filter

151. Which one is forward bias?

152. When Ge crystal is doped with phosphorus atom, then it becomes

p-type

Superconductor

Insulator

n-type

153. The ratio of applied stress to volumetric strain is called

Young’s modulus

None of these

Shear modulus

Bulk modulus

154. In a P-type semiconductor

Major current carriers are electrons

The no. of mobile holes exceeds the no. of mobile acceptors

Major current carriers are mobile holes

Major current carriers are mobile negative ions

155. The part of a transistor which is heavily doped to produce large number of majority carriers is

Emitter

Collector

Any of the above depending on nature of transistor

Base

156. If p-type material of the PN-junction is connected with positive terminal of the battery and n-type material with negative terminal of the battery, it is said to be

Forward biased

Zero biased

Reversed biased

None of these

157. In a good conductor, the energy gap between the conduction band and the valence band is

Infinity

Wide

Zero

Narrow

158. With negative feedback, the returning signal:

Opposes the input signal

Is proportional to output current

Is proportional to differential voltage gain

Aids the input signal

159. Depletion layer consists of

Electrons

Protons

Immobile ions

Mobile ions

160. When aluminum is added as an impurity to silicon, then resulting material is

p-type conductor

p-type semiconductor

n-type conductor

n-type semiconductor

161. In p-n-p transistor the collector current is

Equal to emitter current

Greater than emitter current

Any of above

Slightly less than emitter current

162. The whole structure obtained by the repetition of unit cell is known as

All of these

Crystal lattice

Ore

Unit cell

163. What input values will cause an AND logic gate to produce a HIGH output?

At least one input is LOW

All inputs are LOW

At least one input is HIGH

All inputs are HIGH

164. In p-type semiconductor

Major carrier is mobile negative ions

Major carrier is mobile holes

The number of mobile holes exceeds the number of acceptors

Major current carrier is electrons

165. N-type crystal is

Positively charged

Negative charged

Neutral

None of these

166. The ratio β shows the

None of these

Current gain

Voltage gain

Input resistance

167. Photodiode is used for

Emission of light

None of these

Detection of light

Light display

168. Radio waves of constant amplitude can be generated with

Rectifier

Filter

FET

Oscillator

169. In a P-type semiconductor

Major current carriers are mobile negative ions

Major current carriers are electrons

Major current carriers are mobile holes

The no. of mobile holes exceeds the no. of mobile acceptors

170. The simplest type of rectification known as half wave rectification is obtained by

Using a Coolidge tube

Suppressing the harmonics in A.C voltage

Suppressing half wave of A.C supply by using diode

Using a transistor

171. The basic logic gate whose output is the complement of the input is the:

INVERTER gate

OR gate

AND gate

Comparator

172. The units of modulus of elasticity are same as that of

None of these

Strain

Force

Stress

173. A NAND gate has:

LOW inputs and a HIGH output

None of these

HIGH inputs and a HIGH output

LOW inputs and a LOW output

174. The device or circuit used for conversion of A.C. into D.C. is called

Converter

A rectifier

An amplifier

Filtering circuit

175. In half wave rectification

Current flows in pulses

None of these

Current flows in one directions

Only half cycle is used

176. If a signal passing through a gate is inhibited by sending a low into one of the inputs, and the output is HIGH, the gate is a(n):

NAND

NOR

AND

177. At room temperature, a p-type semi-conductor has

Large number of free electrons and few holes

Large number of holes and few electrons

Equal number of free electrons and holes

Large number of holes and electrons

You Can Learn and Gain more Knowledge through our Online Quiz and Testing system Just Search your desired Preparation subject at Gotest.

Physics Vactors And Equilibrium Online Mcqs Test
Physics Alternating Current Online Mcqs Test
Physics Fluid Dynamics Online Mcqs Test
Physics Dawn of Modern Physics Online Mcqs Test
Physics Electromagnetism Online Mcqs Test
Physics Current Electricity Online Mcqs Test
Thermodynamics Online Mcqs Test
Physics Waves Online Mcqs Test
Physics Rotational and Circular Motion Online Mcqs Test
Physics Work and Energy Online Mcqs Test

Malik TahirLast Updated: October 13, 2025

Physics Electronics Online Mcqs Test

Important Electronics Question and Answer

Physics Electronics Practice Test Online With Explanation

Related Posts

Malik Tahir

Leave a Reply Cancel reply