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ECAT Physics Electronics MCQS Online Test

Maan AliLast Updated: April 19, 2025

Physics Electronics MCQS Online Test

ECAT Physics Electronics Chapter Online Test

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:	ECAT Entry Test Physics Online Test Interview Questions about Physics All Universities Entrance Test Recruitments Tests

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

4.9

9.8

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

Suddenly increases

Decreases slowly

Increases slowly

Remain fixed

3. N-type crystal is

None of these

Positively charged

Neutral

Negative charged

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

Dual carriers

Blockers

Majority carriers

Minority carriers

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

Drift of charges

Both drift and diffusion of charges

Diffusion of charges

Depends upon the nature of material

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

Is independent of voltage

Decreased by reverse biasing

Increased by forward biasing

Increased by reverse biasing

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

Rectifier

Oscillator

P-type material

Amplifier

8. Which logic gate is represented by following diagram?

AND

NOR

EOR

9. A n-p-n transistor conducts when

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

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

Both collector and emitter are positive with respect to the base

Both collector and emitter are negative with respect to the base

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

OR gates

AND gates

NAND gates

NOT gates

11. Transistor can be used as

Filter

Full wave rectifier

Amplifier

Half wave rectifier

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

Amplifier

Transistor

Diode

Rectifier

13. The number of junctions in the PNP transistor are

14. In Germanium crystal, impurity donor elements have valiancy

15. In Germanium crystal, impurity donor elements have valiancy

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

Insulators

Conductors

Semiconductors

Superconductors

17. Which is normal used of transistor?

P-type material

Switching device

Rectifier

Diode

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

None of these

Man hundred

Hundreds

Thousands

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

Amplifier

Filter

Logic gates

Oscillator

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

OR gates only

AND gates, OR gates, and NOT gates

AND gates and NOT gates

Or gates and NOT gates

21. The energy band gap is maximum in

Semiconductors

Insulators

Superconductors

Metals

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

Slightly less than emitter current

Any of above

Equal to emitter current

Greater than emitter current

23. In the transistor schematic symbol, the arrow

Is locate on the collector

Is located on the emitter

Point from north to south

Is located on the base

24. Diode can work as

Modulator

Rectifier

Oscillator

Multivibrator

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

The light emitting diode

The switch

The photo diodes

Solar cells

26. Which one is reverse-biased?

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

NOT gate

OR gate

AND gate

XOR gate

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

Large number of holes and few electrons

Equal number of free electrons and holes

Large number of holes and electrons

Large number of free electrons and few holes

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

Is independent of voltage

Increased by reverse biasing

Decreased by reverse biasing

Increased by forward biasing

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

Filter

Oscillator

Logic gates

Amplifier

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

Potential is maximum

Electric field is zero

Potential is zero

Electric field is maximum

32. The operation of a transistor requires

None of these

That the collector be heated

That the base be heated

That the emitter be heated

33. In insulators

Valence band is partially filled with electrons

Conduction band is empty and valence band is filled with electrons

Conduction band is partially filled with electrons

Conduction band is filled with electrons and valence bad is empty

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

Neutrons

Extra electrons

Protons

Missing of electrons

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

Narrow

Infinity

Zero

Wide

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

It has low resistance to the current flow when forward biased

Its conductivity increases with rise of temperature

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

It has high resistance to the current flow when reverse biased

37. The least doped region in a transistor is

Emitter

Base

Collector

Either emitter or collector

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

P-type material

Super conductor

Semiconductor

N-type material

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

Potential is zero

Potential is maximum

Electric field is zero

Electric field is maximum

40. When n-type of semiconductor is heated,

Number of electrons and holes increases equally

Number of holes increases while that of holes decreases

Number of electrons and holes remains same

Number of electrons increases while that of holes decreases

41. n-type semiconductor if formed

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

From pure Si crystal

From pure Ge crystal

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

42. Polythene, potystrene and nylon are examples of

Amorphous solids

Crystalline solids

Polymeric solids

Glassy solids

43. Reverse bias applied on a junction diode

Lowers the potential barrier

Increases the majority carrier current

Raises the potential barrier

Increase the minority carrier current

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

NOT gate

OR gate

AND gate

NOR gate

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

n-type conductor

p-type semiconductor

n-type semiconductor

p-type conductor

46. In semiconductors at a room temperature

The valence band is completely filled

The conduction band is completely empty

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

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

Ohms

Several mega ohms

Kilo ohms

Mega ohms

48. Acceptor and donor impurities donate

p-carriers and n-carriers respectively

n-carriers only

n-carriers and p-carriers respectively

p-carriers only

49. The energy band gap is maximum in

Semiconductors

Superconductors

Metals

Insulators

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

Greater than one

Of zero

Equal to one

Less than one

51. LDR means:

Low degree resistor

None of these

Light dependent resistance

Low degree radiations

52. 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

Base

Collector

Emitter

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

In forward bias

In reverse bias

None of these

To A.C.

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

4.9

9.8

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

Insulator

Superconductor

Semiconductor

None of these

56. 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

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

None of these

Shear stress

Compress ional stress

Tensile stress

58. Photodiode is used for

Light display

Emission of light

Detection of light

None of these

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

Diffusion region

None of these

Depletion region

Charged region

60. The working of transistor as amplifier is similar to

Triode vacuum tube

Step up transformer

Three diodes in common

Step down transformer

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

Almost negligible

Very low

Very high

Zero

62. Identify the correct statement about minority carriers

Free electrons in n-type and p-type

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

63. Photovoltaic cell produces electrical energy from

Chemical energy

None of these

Heat energy

Light energy

64. 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):

NOR

NAND

AND

65. Reverse bias applied on a junction diode

Lowers the potential barrier

Increases the majority carrier current

Increase the minority carrier current

Raises the potential barrier

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

mix

any of above

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

Modulus of electricity

Young’s modulus

None of these

Bulk’s modulus

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

All of these

Gallium

Boron

Aluminum

69. Arsenic, antimony or phosphorus are impurities of

n-type

p-type

may be p-type or n-type

None of these

70. At absolute zero, Si acts as

Non-metal

Insulator

None of these

Metal

71. The critical temperature for mercury is

3.72 K

4.2 K

7.2 K

1.18 K

72. NAND gate is

Not a universal gate

A basic gate

A basic universal gate

A universal gate

73. Zener breakdown in a semiconductor diode occurs when

Potential barrier is reduced to zero

Forward bias exceeds certain value

Reverse bias exceeds certain value

Forward current exceeds certain value

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

Inductor

On switch

Off switch

Capacitor

75. A transistor consists of

Two PN-junctions

Three PN-junctions

Four PN-junctions

One PN-junction

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

None of these

Collector

Emitter

Base

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

Neutrons

Electrons

Holes

Protons

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

Zero amplitude

Constant amplitude

Unit amplitude

Variable amplitude

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

None of these

Nanosecond

Microsecond

Millisecond

80. 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 be base

Holes move from emitter to base

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

Common collector configuration

Common base configuration

None of these

Common emitter configuration

82. 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 emitter to base

Holes move from base to emitter

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

Collector

Base

Emitter

Any of above

84. With negative feedback, the returning signal:

Is proportional to differential voltage gain

Aids the input signal

Opposes the input signal

Is proportional to output current

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

0.67 V

0.7 V

0.9 V

0.5 V

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

1 cm

1 mm

10¯¹² cm

10¯⁶ cm

87. Young’s modulus for copper is

None of these

91 x 10 Nm¯²

70 x 10 Nm¯²

110 Nm¯²

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

Magnification

All of these

Amplification

Rectification

89. An OP-AMPs can amplify

None of these

Both A.C. & D.C.

A.C.

D.C.

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

All of above

Boron

Gallium

Aluminum

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

Each of them increases

Copper increases and germanium decreases

Copper decreases and germanium increases

Each of them decreases

92. A substance which have empty conduction band is called

None of these

Insulator

Semiconductor

Conductor

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

AND gate

OR gate

NAND gate

NOT gate

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

Decreases and then increases

Remains unchanged

Decreases

Increases

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

An amplifier

A rectifier

Converter

Filtering circuit

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

Holes and electrons

Electrons and holes

Protons and electrons

Electrons and protons

97. In a semiconductor, the mobility of holes is

Greater than electrons

Equal to electrons

Less than electrons

None

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

Extra electrons

Missing electrons

Protons

Neutrons

99. When NPN transistor is used as an amplifier

Electrons move from collector to base

Electrons move from emitter to base

Electrons move from base to emitter

Holes move from base to emitter

100. Which one is forward bias?

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

None of these

Require more current

Works efficiently

Damaged

102. In forward bias the width of potential barrier

Decreases

Increases

No effect

Remains same

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

n-type conductor

p-type semiconductor

n-type semiconductor

p-type conductor

104. In half wave rectification

Current flows in pulses

Only half cycle is used

Current flows in one directions

None of these

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

Base

Emitter

Collector

Can be any of the above three

106. The forward resistance of the diode is

Ohms

Few ohms

Many ohms

None of these

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

p-type

Intrinsic

Extrinsic

n-type

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

None of these

Force

Stress

Strain

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

Copper decreases and germanium increases

Each of them decreases

Copper increases and germanium decreases

Each of them increases

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

Indium

Phosphorus

Antimony

Arsenic

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

Stress

Strain

Force

None of these

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

Infinity

None of these

Zero

Almost zero

113. 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

114. 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

None of these

Reversed biased

Zero biased

Forward biased

115. Semi-conductor germanium and silicon are

Pentavalent

Trivalent

Divalent

Tetravalent

116. A diode as a rectifier converts:

High voltage to low voltage

A.C. into D.C.

D.C. into A.C.

Low voltage to high voltage

117. 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

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

Unit cell

Ore

Crystal lattice

All of these

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

INVERTER gate

AND gate

Comparator

OR gate

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

Temperature

Doping density

Forward bias

Diode design

121. A diode as a rectifier converts:

High voltage to low voltage

D.C. into A.C.

A.C. into D.C.

Low voltage to high voltage

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

Extrinsic

n-type

Intrinsic

p-type

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

N-type conductor

None of these

N-type semiconductor

P-type semiconductor

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

Holes

None of these

Neutrons

Electrons

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

Both are at the same potential

Both are at the high potential

Inverting terminal is at high potential

Non-inverting terminal is at high potential

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

Free electrons

Valence electrons

Tightly bound electrons

None of these

127. To use a transistor as an amplifier

No bias voltages are required

Both junctions are reverse biased

Both junctions are forward biased

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

128. 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

129. Depletion layer consists of

Electrons

Immobile ions

Mobile ions

Protons

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

Base

Collector

Emitter

Any of the above depending on nature of transistor

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

Decreases and then increases

Remains unchanged

Decreases

Increases

132. When the output of OR gate is 1

Only if both inputs are 1

If both inputs are zero

If either or both inputs are 1

If either input is zero

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

Insulator

Alloy

Semiconductor

Conductor

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

It offers a very low open loop gain all of above

It offers a very low output resistance

It offers a very high inputs resistance to the input current

None of these

135. Radio waves of constant amplitude can be generated with

Oscillator

FET

Filter

Rectifier

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

Aluminum

Phosphorus

Antimony

Arsenic

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

Increase its life

Increase its electrical resistivity

Enable it to Telerate higher voltage

Increases its electrical conductivity

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

Computers

Electric generations

Electric motors

Transformers

139. In p-type semiconductor

Major carrier is mobile holes

The number of mobile holes exceeds the number of acceptors

Major carrier is mobile negative ions

Major current carrier is electrons

140. 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

Increase its life

Increase its electrical conductivity

141. A NAND gate has:

LOW inputs and a LOW output

HIGH inputs and a HIGH output

LOW inputs and a HIGH output

None of these

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

Large number of holes and electrons

Large number of holes and few electrons

Equal number of free electrons and holes

Large number of free electrons and few holes

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

Remains constant

Decreases

Increases

First A and B

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

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

Raises the potential barrier

Increase the majority carrier current

Lowers the potential barrier

Increase the minority carrier current

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

Young’s modulus

Shear modulus

None of these

Bulk modulus

147. The thickness of the base is equal to

Mean of thickness of emitter and collector

Thickness of collector

Thickness of emitter

Very small as compared to the thickness of emitter and collector

148. The positive sign of gain indicates that

Input and out signals are not in phase

Input and out signals are in phase

May be in phase or not

None of these

149. Depletion region of a junction is formed

Under forward bias

During the manufacturing process

Under reverse bias

When temperature varies

150. 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 forward based

Potential barrier in depletion layer increases

Diode is reverse biased

Potential barrier in depletion layer remains unchanged

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

Gamma Rays

Electromagnetic Waves

Transverse Waves

x-rays

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

Resistor is used

Solvent is used

None of these

Capacitor is used

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

Detector

Oscillator

None of these

Rectifier

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

Diode is reverse biased

Diode is forward biased

Diode is neutralized

None of these

155. The ratio β represents

156. The least doped region in a transistor is

Base

Collector

Emitter

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

Antimony

Phosphorus

Arsenic

Aluminum

158. In a PN junction

Undetermined

High potential at N side and low potential at P side

High potential at P side and low potential at N side

P and N both are at same potential

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

Aluminum

Boron

Gold

Phosphorus

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

Resistance of both decreases

Resistance of copper decreases while that of germanium increases

Resistance of copper increases while that of germanium decreases

Resistance of both increases

161. The ratio β shows the

Current gain

None of these

Input resistance

Voltage gain

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

Reference voltage on the other

Virtual input

Non-inverting voltage at output

Output

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

Extra electrons

Protons

Neutrons

Missing electrons

164. Light emitting diode work when it is

Forward biases

Reverse biased

None of these

Both

165. 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

Band levels

Hidden energy states

None of these

166. In a n-p-n transistor:

Negative charge moves from collector to base

Holes move from base to collector

Negative charge moves from emitter to base

Holes move from emitter to base

167. Application of photodiode is/are

Logic gates

Detection of visible and invisible radiations

Automatic switching

None of these

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

High

Zero

None of these

Low

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

Suppressing the harmonics in A.C voltage

Suppressing half wave of A.C supply by using diode

Using a transistor

Using a Coolidge tube

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

p-type

Superconductor

n-type

Insulator

171. In insulators

Conduction band is filled with electrons and valence band is empty

Conduction band is empty and valence band is filled with electrons

Conduction band is partially filled with electrons

Valence band is partially filled with electrons

172. 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

173. Symbol represents

NOT gate

XNOR gate

NAND gate

NOR gate

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

At least one input is LOW

All inputs are LOW

All inputs are HIGH

At least one input is HIGH

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

180° Phase shift

120° Phase shift

90° Phase shift

No Phase shift

176. Non-inverting amplifier circuits have

A very low input impedance

None of these

A low output impedance

A very high input impedance

177. At absolute zero, Si acts as

None of these

Metal

Insulator

Non-metal

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Maan AliLast Updated: April 19, 2025

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3 Comments

khansa noreen says:

September 11, 2020 at 10:12 pm

i want to know that how I prepare my entry test?

Name (required) says:

June 30, 2017 at 10:25 pm

assalam o alaikum mot of the answers are wrong…kindly check it

1. Humza arain says:
  
  January 7, 2021 at 4:27 pm
  
  Humza arain

ECAT Physics Electronics MCQS Online Test

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