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

Aluminum

Antimony

Phosphorus

Arsenic

2. Which is normal used of transistor?

Switching device

Diode

Rectifier

P-type material

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

Mega ohms

Kilo ohms

Ohms

Several mega ohms

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

Increases

Decreases and then increases

Remains unchanged

Decreases

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

Unit cell

Ore

Crystal lattice

All of these

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

Boron

Aluminum

Gold

Phosphorus

7. Arsenic, antimony or phosphorus are impurities of

p-type

None of these

n-type

may be p-type or n-type

8. When the output of OR gate is 1

If both inputs are zero

If either input is zero

If either or both inputs are 1

Only if both inputs are 1

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

Extra electrons

Neutrons

Missing electrons

Protons

10. Polythene, potystrene and nylon are examples of

Glassy solids

Polymeric solids

Amorphous solids

Crystalline solids

11. NAND gate is

Not a universal gate

A universal gate

A basic universal gate

A basic gate

12. In forward bias the width of potential barrier

Increases

Remains same

Decreases

No effect

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

14. The forward resistance of the diode is

Many ohms

Ohms

Few ohms

None of these

15. 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

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

Forward bias

Diode design

Doping density

Temperature

17. In a semiconductor, the mobility of holes is

Less than electrons

Greater than electrons

Equal to electrons

None

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

Increases slowly

Remain fixed

Decreases slowly

Suddenly increases

19. Zener breakdown in a semiconductor diode occurs when

Potential barrier is reduced to zero

Forward current exceeds certain value

Reverse bias exceeds certain value

Forward bias exceeds certain value

20. A substance which have empty conduction band is called

None of these

Semiconductor

Insulator

Conductor

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

mix

any of above

22. Which one is reverse-biased?

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

Decreases

Remains constant

First A and B

Increases

24. The least doped region in a transistor is

Collector

Either emitter or collector

Base

Emitter

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

Collector

Base

Emitter

Any of the above depending on nature of transistor

26. Symbol represents

NOT gate

XNOR gate

NAND gate

NOR gate

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

n-type conductor

n-type semiconductor

p-type semiconductor

p-type conductor

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

Resistance of both increases

Resistance of copper decreases while that of germanium increases

Resistance of copper increases while that of germanium decreases

Resistance of both decreases

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

Man hundred

None of these

Hundreds

Thousands

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

All of these

Aluminum

Gallium

Boron

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

Slightly less than emitter current

Any of above

Greater than emitter current

Equal to emitter current

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

None of these

Stress

Force

Strain

33. Light emitting diode work when it is

Reverse biased

Both

Forward biases

None of these

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

Comparator

AND gate

INVERTER gate

OR gate

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

Greater than one

Of zero

Equal to one

Less than one

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

NOT gate

XOR gate

AND gate

OR gate

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

Copper increases and germanium decreases

Copper decreases and germanium increases

Each of them decreases

Each of them increases

38. A NAND gate has:

LOW inputs and a HIGH output

HIGH inputs and a HIGH output

None of these

LOW inputs and a LOW output

39. Depletion region of a junction is formed

During the manufacturing process

Under forward bias

Under reverse bias

When temperature varies

40. 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

41. Radio waves of constant amplitude can be generated with

Rectifier

FET

Oscillator

Filter

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

n-type conductor

p-type conductor

p-type semiconductor

n-type semiconductor

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

Constant amplitude

Zero amplitude

Variable amplitude

Unit amplitude

44. At absolute zero, Si acts as

Insulator

Metal

Non-metal

None of these

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

Transformers

Computers

Electric generations

Electric motors

46. In half wave rectification

None of these

Current flows in pulses

Current flows in one directions

Only half cycle is used

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

Indium

Phosphorus

Antimony

Arsenic

48. The positive sign of gain indicates that

May be in phase or not

Input and out signals are not in phase

Input and out signals are in phase

None of these

49. 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

Potential barrier in depletion layer increases

Diode is reverse biased

Diode is forward based

Potential barrier in depletion layer remains unchanged

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

N-type semiconductor

None of these

N-type conductor

P-type semiconductor

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

At least one input is LOW

At least one input is HIGH

All inputs are LOW

All inputs are HIGH

52. Which one is forward bias?

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

Base

Collector

Emitter

Can be any of the above three

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

Electrons move from base to collector

Holes move from emitter be base

Holes move from emitter to base

Holes move from base to emitter

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

Transistor

Amplifier

Rectifier

Diode

56. A diode as a rectifier converts:

D.C. into A.C.

High voltage to low voltage

Low voltage to high voltage

A.C. into D.C.

57. 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

AND

NOR

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

Can be any of the above three

Emitter

Collector

Base

59. The critical temperature for mercury is

7.2 K

1.18 K

3.72 K

4.2 K

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

None of these

Young’s modulus

Bulk modulus

Shear modulus

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

4.9

9.8

62. In semiconductors at a room temperature

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

The conduction band is completely empty

The valence band is completely filled

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

63. Young’s modulus for copper is

None of these

110 Nm¯²

70 x 10 Nm¯²

91 x 10 Nm¯²

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

10¯⁶ cm

1 cm

10¯¹² cm

1 mm

65. Depletion layer consists of

Electrons

Mobile ions

Protons

Immobile ions

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

Filter

Amplifier

Oscillator

Logic gates

67. In Germanium crystal, impurity donor elements have valiancy

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

Low

High

None of these

Zero

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

Collector

Base

Emitter

Any of above

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

Potential is maximum

Electric field is zero

Electric field is maximum

Potential is zero

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

Semiconductor

N-type material

P-type material

Super conductor

72. 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

73. In a P-type semiconductor

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

Major current carriers are electrons

Major current carriers are mobile negative ions

Major current carriers are mobile holes

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

Charged region

None of these

Diffusion region

Depletion region

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

n-type

Extrinsic

Intrinsic

p-type

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

Almost zero

Zero

None of these

Infinity

77. 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 valence band is completely filled

The conduction band is completely empty

78. Which logic gate is represented by following diagram?

NOR

AND

EOR

79. In the transistor schematic symbol, the arrow

Is locate on the collector

Point from north to south

Is located on the emitter

Is located on the base

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

Holes

Neutrons

Electrons

None of these

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

All of above

Aluminum

Gallium

Boron

82. The number of junctions in the PNP transistor are

83. The operation of a transistor requires

None of these

That the base be heated

That the collector be heated

That the emitter be heated

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

Equal number of free electrons and holes

Large number of holes and electrons

Large number of free electrons and few holes

Large number of holes and few electrons

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

None of these

Works efficiently

Damaged

Require more current

86. When n-type of semiconductor is heated,

Number of electrons and holes increases equally

Number of electrons and holes remains same

Number of electrons increases while that of holes decreases

Number of holes increases while that of holes decreases

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

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

It has low resistance to the current flow when forward biased

It has high resistance to the current flow when reverse biased

Its conductivity increases with rise of temperature

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

Common base configuration

Common collector configuration

None of these

Common emitter configuration

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

Missing electrons

Neutrons

Extra electrons

Protons

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

Compress ional stress

Tensile stress

None of these

Shear stress

91. 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

92. Application of photodiode is/are

Automatic switching

None of these

Logic gates

Detection of visible and invisible radiations

93. At absolute zero, Si acts as

Metal

Non-metal

None of these

Insulator

94. The least doped region in a transistor is

Collector

Emitter

Base

95. A diode as a rectifier converts:

Low voltage to high voltage

High voltage to low voltage

D.C. into A.C.

A.C. into D.C.

96. 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

None of these

Zero biased

Reversed biased

97. Diode can work as

Modulator

Oscillator

Rectifier

Multivibrator

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

Output

Virtual input

Non-inverting voltage at output

Reference voltage on the other

99. In insulators

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

Conduction band is filled with electrons and valence bad is empty

100. In a P-type semiconductor

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

Major current carriers are mobile negative ions

Major current carriers are mobile holes

Major current carriers are electrons

101. In Germanium crystal, impurity donor elements have valiancy

102. 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

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

Solar cells

The switch

The photo diodes

The light emitting diode

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

9.8

4.9

105. In a PN junction

High potential at P side and low potential at N side

High potential at N side and low potential at P side

Undetermined

P and N both are at same potential

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

Superconductors

Conductors

Insulators

Semiconductors

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

p-type

n-type

Extrinsic

Intrinsic

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

Microsecond

None of these

Millisecond

Nanosecond

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

Depends upon the nature of material

Both drift and diffusion of charges

Drift of charges

Diffusion of charges

110. A transistor consists of

Four PN-junctions

Two PN-junctions

One PN-junction

Three PN-junctions

111. Reverse bias applied on a junction diode

Lowers the potential barrier

Raises the potential barrier

Increases the majority carrier current

Increase the minority carrier current

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

Zero

Almost negligible

Very low

Very high

113. n-type semiconductor if formed

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

From pure Si crystal

From pure Ge crystal

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

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

Emitter

Base

Collector

None of these

115. N-type crystal is

Neutral

Positively charged

None of these

Negative charged

116. 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

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

0.9 V

0.67 V

0.5 V

0.7 V

118. Acceptor and donor impurities donate

n-carriers only

p-carriers and n-carriers respectively

p-carriers only

n-carriers and p-carriers respectively

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

Neutrons

Missing of electrons

Protons

Extra electrons

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

Electrons

Protons

Holes

Neutrons

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

AND gates, OR gates, and NOT gates

AND gates and NOT gates

OR gates only

Or gates and NOT gates

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

Alloy

Semiconductor

Insulator

Conductor

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

P-type material

Oscillator

Amplifier

Rectifier

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

Both are at the high potential

Inverting terminal is at high potential

Non-inverting terminal is at high potential

Both are at the same potential

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

AND gate

NOR gate

OR gate

NOT gate

126. The ratio β represents

127. With negative feedback, the returning signal:

Is proportional to differential voltage gain

Is proportional to output current

Aids the input signal

Opposes the input signal

128. The ratio β shows the

Voltage gain

Current gain

Input resistance

None of these

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

Insulator

p-type

Superconductor

n-type

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

Wide

Zero

Narrow

Infinity

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

No Phase shift

180° Phase shift

120° Phase shift

90° Phase shift

132. The thickness of the base is equal to

Thickness of collector

Mean of thickness of emitter and collector

Thickness of emitter

Very small as compared to the thickness of emitter and collector

133. The energy band gap is maximum in

Semiconductors

Superconductors

Metals

Insulators

134. Transistor can be used as

Amplifier

Filter

Full wave rectifier

Half wave rectifier

135. LDR means:

Low degree resistor

Low degree radiations

Light dependent resistance

None of these

136. Non-inverting amplifier circuits have

A low output impedance

A very high input impedance

A very low input impedance

None of these

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

Arsenic

Phosphorus

Antimony

Aluminum

138. In a n-p-n transistor:

Holes move from emitter to base

Negative charge moves from emitter to base

Holes move from base to collector

Negative charge moves from collector to base

139. Semi-conductor germanium and silicon are

Trivalent

Pentavalent

Divalent

Tetravalent

140. In insulators

Conduction band is partially filled with electrons

Conduction band is filled with electrons and valence band is empty

Valence band is partially filled with electrons

Conduction band is empty and valence band is filled with electrons

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

Decreases and then increases

Remains unchanged

Increases

Decreases

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

On switch

Capacitor

Off switch

Inductor

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

Large number of free electrons and few holes

Equal number of free electrons and holes

Large number of holes and electrons

Large number of holes and few electrons

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

An amplifier

Converter

A rectifier

Filtering circuit

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

Amplifier

Filter

Logic gates

Oscillator

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

Modulus of electricity

Bulk’s modulus

Young’s modulus

None of these

147. 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

148. 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 neutralized

Diode is reverse biased

Diode is forward biased

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

To A.C.

In forward bias

In reverse bias

None of these

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

Enable it to Telerate higher voltage

Increase its electrical resistivity

Increase its electrical conductivity

Increase its life

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

Valence electrons

None of these

Free electrons

Tightly bound electrons

152. Photovoltaic cell produces electrical energy from

Light energy

Chemical energy

Heat energy

None of these

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

Transverse Waves

x-rays

Electromagnetic Waves

Gamma Rays

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

Stress

Force

Strain

None of these

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

Increase its electrical resistivity

Enable it to Telerate higher voltage

Increases its electrical conductivity

Increase its life

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

Protons and electrons

Electrons and holes

Holes and electrons

Electrons and protons

157. Photodiode is used for

Emission of light

Detection of light

None of these

Light display

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

NOT gate

NAND gate

OR gate

AND gate

159. An OP-AMPs can amplify

Both A.C. & D.C.

A.C.

D.C.

None of these

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

Is independent of voltage

Increased by reverse biasing

Increased by forward biasing

Decreased by reverse biasing

161. In a n-p-n transistor:

Negative charge moves from collector to base

Holes move from emitter to base

Holes move from base to collector

Negative charge moves from emitter to base

162. Identify the correct statement about minority carriers

Holes in n-type and p-type

Free electrons in n-type and p-type

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

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

163. In p-type semiconductor

Major carrier is mobile negative ions

The number of mobile holes exceeds the number of acceptors

Major current carrier is electrons

Major carrier is mobile holes

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

Rectifier

None of these

Detector

Oscillator

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

Dual carriers

Minority carriers

Majority carriers

Blockers

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

OR gates

AND gates

NAND gates

NOT gates

167. Reverse bias applied on a junction diode

Raises the potential barrier

Increase the minority carrier current

Increases the majority carrier current

Lowers the potential barrier

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

Semiconductor

Insulator

None of these

Superconductor

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

Holes move from base to emitter

Electrons move from base to collector

Holes move from emitter to base

170. To use a transistor as an amplifier

No bias voltages are required

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

Both junctions are reverse biased

Both junctions are forward biased

171. The working of transistor as amplifier is similar to

Step up transformer

Three diodes in common

Triode vacuum tube

Step down transformer

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

Rectification

All of these

Magnification

Amplification

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

Capacitor is used

Resistor is used

None of these

Solvent is used

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

Increased by reverse biasing

Decreased by reverse biasing

Is independent of voltage

Increased by forward biasing

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

Each of them decreases

Copper decreases and germanium increases

Each of them increases

Copper increases and germanium decreases

176. When NPN transistor is used as an amplifier

Electrons move from base to emitter

Holes move from base to emitter

Electrons move from collector to base

Electrons move from emitter to base

177. The energy band gap is maximum in

Superconductors

Insulators

Metals

Semiconductors

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