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

Oscillator

Amplifier

Filter

Logic gates

2. LDR means:

Low degree resistor

Light dependent resistance

None of these

Low degree radiations

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

Equal to one

Greater than one

Of zero

Less than one

4. In Germanium crystal, impurity donor elements have valiancy

5. Zener breakdown in a semiconductor diode occurs when

Reverse bias exceeds certain value

Potential barrier is reduced to zero

Forward current exceeds certain value

Forward bias exceeds certain value

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

Hidden energy states

None of these

Band levels

Forbidden energy states

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

Extrinsic

n-type

p-type

Intrinsic

8. In forward bias the width of potential barrier

Increases

Decreases

No effect

Remains same

9. The forward resistance of the diode is

Few ohms

Ohms

Many ohms

None of these

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

Depletion region

Diffusion region

None of these

Charged region

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

None of these

Tensile stress

Compress ional stress

Shear stress

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

None of these

Hundreds

Thousands

Man hundred

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

On switch

Inductor

Off switch

Capacitor

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

15. Acceptor and donor impurities donate

p-carriers only

n-carriers and p-carriers respectively

p-carriers and n-carriers respectively

n-carriers only

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

Equal number of free electrons and holes

Large number of holes and few electrons

Large number of holes and electrons

Large number of free electrons and few holes

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

Stress

Strain

None of these

Force

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

Diode design

Doping density

Forward bias

Temperature

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

Superconductor

n-type

Insulator

p-type

20. The operation of a transistor requires

That the emitter be heated

That the base be heated

That the collector be heated

None of these

21. N-type crystal is

Neutral

None of these

Positively charged

Negative charged

22. Which one is reverse-biased?

23. A transistor consists of

One PN-junction

Two PN-junctions

Three PN-junctions

Four PN-junctions

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

Arsenic

Phosphorus

Antimony

Aluminum

25. Semi-conductor germanium and silicon are

Tetravalent

Pentavalent

Trivalent

Divalent

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

The light emitting diode

The switch

Solar cells

The photo diodes

27. In a semiconductor, the mobility of holes is

Greater than electrons

Less than electrons

Equal to electrons

None

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

Collector

Emitter

Can be any of the above three

Base

29. 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

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

It has high resistance to the current flow when reverse biased

Its conductivity increases with rise of temperature

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

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

All of above

Aluminum

Boron

Gallium

32. In semiconductors at a room temperature

The valence band is completely filled

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

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

Protons

Extra electrons

Neutrons

Missing electrons

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

Any of above

Greater than emitter current

Slightly less than emitter current

Equal to emitter current

35. When NPN transistor is used as an amplifier

Electrons move from emitter to base

Electrons move from base to emitter

Electrons move from collector to base

Holes move from base to emitter

36. Which one is forward bias?

37. The ratio β represents

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

Mega ohms

Several mega ohms

Kilo ohms

Ohms

39. In a P-type semiconductor

Major current carriers are mobile holes

Major current carriers are mobile negative ions

Major current carriers are electrons

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

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

All of these

Amplification

Rectification

Magnification

41. In Germanium crystal, impurity donor elements have valiancy

42. Application of photodiode is/are

Detection of visible and invisible radiations

Automatic switching

Logic gates

None of these

43. The energy band gap is maximum in

Insulators

Semiconductors

Superconductors

Metals

44. 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 base to emitter

Holes move from emitter be base

45. Polythene, potystrene and nylon are examples of

Polymeric solids

Crystalline solids

Glassy solids

Amorphous solids

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

Aluminum

Antimony

Arsenic

Phosphorus

47. Diode can work as

Oscillator

Modulator

Rectifier

Multivibrator

48. In a n-p-n transistor:

Negative charge moves from collector to base

Holes move from emitter to base

Negative charge moves from emitter to base

Holes move from base to collector

49. 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

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

Remains constant

Increases

First A and B

Decreases

51. At absolute zero, Si acts as

Non-metal

None of these

Metal

Insulator

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

Works efficiently

None of these

Require more current

Damaged

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

Base

Any of the above depending on nature of transistor

Emitter

Collector

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

Infinity

Narrow

Zero

Wide

55. A NAND gate has:

LOW inputs and a LOW output

HIGH inputs and a HIGH output

None of these

LOW inputs and a HIGH output

56. 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

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

None of these

It offers a very low output resistance

It offers a very low open loop gain all of above

It offers a very high inputs resistance to the input current

58. Symbol represents

XNOR gate

NOR gate

NAND gate

NOT gate

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

Gold

Aluminum

Boron

Phosphorus

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

AND gates and NOT gates

Or gates and NOT gates

AND gates, OR gates, and NOT gates

OR gates only

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

Transformers

Electric motors

Electric generations

Computers

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

Each of them increases

Copper decreases and germanium increases

Copper increases and germanium decreases

Each of them decreases

63. Depletion region of a junction is formed

During the manufacturing process

Under forward bias

When temperature varies

Under reverse bias

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

1 mm

10¯⁶ cm

1 cm

10¯¹² cm

65. Transistor can be used as

Filter

Half wave rectifier

Full wave rectifier

Amplifier

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

NAND gate

NOT gate

AND gate

OR gate

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

Oscillator

Rectifier

None of these

Detector

68. NAND gate is

Not a universal gate

A basic universal gate

A basic gate

A universal gate

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

Minority carriers

Dual carriers

Blockers

Majority carriers

70. In a PN junction

High potential at P side and low potential at N side

Undetermined

High potential at N side and low potential at P side

P and N both are at same potential

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

Oscillator

Amplifier

P-type material

Rectifier

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

None of these

Infinity

Zero

Almost zero

73. A piece 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

74. When n-type of semiconductor is heated,

Number of electrons and holes remains same

Number of electrons increases while that of holes decreases

Number of electrons and holes increases equally

Number of holes increases while that of holes decreases

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

All of these

Unit cell

Ore

Crystal lattice

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

In forward bias

To A.C.

None of these

In reverse bias

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

Decreases

Increases

Decreases and then increases

Remains unchanged

78. 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

Potential barrier in depletion layer remains unchanged

Diode is reverse biased

79. 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

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

NOR gate

OR gate

NOT gate

AND gate

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

Diffusion of charges

Drift of charges

Depends upon the nature of material

Both drift and diffusion of charges

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

Using a transistor

Suppressing half wave of A.C supply by using diode

Using a Coolidge tube

Suppressing the harmonics in A.C voltage

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

Solvent is used

None of these

Resistor is used

Capacitor is used

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

Constant amplitude

Variable amplitude

Zero amplitude

Unit amplitude

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

Is independent of voltage

Increased by forward biasing

Increased by reverse biasing

Decreased by reverse biasing

86. 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

87. The least doped region in a transistor is

Emitter

Collector

Base

88. In the transistor schematic symbol, the arrow

Point from north to south

Is located on the base

Is located on the emitter

Is locate on the collector

89. At absolute zero, Si acts as

None of these

Metal

Non-metal

Insulator

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

Extra electrons

Neutrons

Protons

Missing of electrons

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

x-rays

Gamma Rays

Transverse Waves

Electromagnetic Waves

92. 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

93. Light emitting diode work when it is

None of these

Reverse biased

Both

Forward biases

94. The thickness of the base is equal to

Thickness of collector

Thickness of emitter

Mean of thickness of emitter and collector

Very small as compared to the thickness of emitter and collector

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

Potential is maximum

Potential is zero

Electric field is maximum

Electric field is zero

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

Semiconductor

Conductor

Alloy

Insulator

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

NOT gate

XOR gate

OR gate

AND gate

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

Valence electrons

Free electrons

Tightly bound electrons

None of these

99. In a n-p-n transistor:

Holes move from base to collector

Negative charge moves from collector to base

Holes move from emitter to base

Negative charge moves from emitter to base

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

Comparator

OR gate

AND gate

INVERTER gate

101. Identify the correct statement about minority carriers

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

Holes in n-type and p-type

102. Radio waves of constant amplitude can be generated with

Oscillator

Filter

FET

Rectifier

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

Boron

All of these

Gallium

Aluminum

104. Which logic gate is represented by following diagram?

EOR

NOR

AND

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

Equal number of free electrons and holes

Large number of holes and few electrons

Large number of holes and electrons

Large number of free electrons and few holes

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

Zero

High

None of these

Low

107. 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

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

Rectifier

Diode

Transistor

Amplifier

109. 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

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

Increase its electrical resistivity

Increase its electrical conductivity

Enable it to Telerate higher voltage

Increase its life

111. n-type semiconductor if formed

From pure Si crystal

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

From pure Ge crystal

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

112. In insulators

Conduction band is filled with electrons and valence bad is empty

Conduction band is empty and valence band is filled with electrons

Valence band is partially filled with electrons

Conduction band is partially filled with electrons

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

Logic gates

Amplifier

Filter

Oscillator

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

Any of above

Collector

Emitter

Base

115. The least doped region in a transistor is

Emitter

Collector

Either emitter or collector

Base

116. 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 resistivity

Increases its electrical conductivity

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

Both are at the high potential

Both are at the same potential

Inverting terminal is at high potential

Non-inverting terminal is at high potential

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

Electrons

Holes

Protons

Neutrons

119. The number of junctions in the PNP transistor are

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

n-type

p-type

Intrinsic

Extrinsic

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

n-type conductor

p-type conductor

p-type semiconductor

n-type semiconductor

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

Base

Collector

None of these

Emitter

123. Young’s modulus for copper is

70 x 10 Nm¯²

None of these

110 Nm¯²

91 x 10 Nm¯²

124. The ratio β shows the

None of these

Voltage gain

Current gain

Input resistance

125. An OP-AMPs can amplify

D.C.

None of these

Both A.C. & D.C.

A.C.

126. A diode as a rectifier converts:

A.C. into D.C.

High voltage to low voltage

Low voltage to high voltage

D.C. into A.C.

127. Photovoltaic cell produces electrical energy from

Light energy

None of these

Chemical energy

Heat energy

128. Photodiode is used for

Emission of light

Light display

Detection of light

None of these

129. With negative feedback, the returning signal:

Opposes the input signal

Is proportional to differential voltage gain

Is proportional to output current

Aids the input signal

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

Suddenly increases

Remain fixed

Increases slowly

Decreases slowly

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

Decreases

Decreases and then increases

Increases

Remains unchanged

132. 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

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

Shear modulus

Bulk modulus

Young’s modulus

None of these

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

9.8

4.9

135. The energy band gap is maximum in

Insulators

Metals

Semiconductors

Superconductors

136. 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

Collector

Emitter

Base

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

Filtering circuit

A rectifier

An amplifier

Converter

138. A diode as a rectifier converts:

A.C. into D.C.

Low voltage to high voltage

D.C. into A.C.

High voltage to low voltage

139. 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 neutralized

Diode is reverse biased

None of these

Diode is forward biased

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

120° Phase shift

No Phase shift

180° Phase shift

90° Phase shift

141. The critical temperature for mercury is

7.2 K

4.2 K

1.18 K

3.72 K

142. A substance which have empty conduction band is called

None of these

Conductor

Insulator

Semiconductor

143. 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

Reversed biased

Zero biased

None of these

Forward biased

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

Very low

Almost negligible

Very high

Zero

145. Non-inverting amplifier circuits have

None of these

A very high input impedance

A very low input impedance

A low output impedance

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

Neutrons

None of these

Electrons

Holes

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

Insulators

Superconductors

Conductors

Semiconductors

148. 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

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

Microsecond

Nanosecond

None of these

Millisecond

150. Depletion layer consists of

Mobile ions

Immobile ions

Electrons

Protons

151. In insulators

Conduction band is empty and valence band is filled with electrons

Conduction band is filled with electrons and valence band is empty

Valence band is partially filled with electrons

Conduction band is partially filled with electrons

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

All inputs are HIGH

At least one input is LOW

All inputs are LOW

At least one input is HIGH

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

Holes and electrons

Electrons and holes

Electrons and protons

Protons and electrons

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

p-type semiconductor

p-type conductor

n-type conductor

n-type semiconductor

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

Strain

Stress

Force

None of these

156. When the output of OR gate is 1

If either or both inputs are 1

If either input is zero

If both inputs are zero

Only if both inputs are 1

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

any of above

mix

158. 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

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

0.9 V

0.5 V

0.7 V

0.67 V

160. To use a transistor as an amplifier

Both junctions are forward biased

Both junctions are reverse biased

No bias voltages are required

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

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

4.9

9.8

162. 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 holes

Major current carriers are mobile negative ions

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

Arsenic

Antimony

Phosphorus

Indium

164. 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

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

Electric field is zero

Potential is zero

Potential is maximum

Electric field is maximum

166. The working of transistor as amplifier is similar to

Three diodes in common

Step up transformer

Step down transformer

Triode vacuum tube

167. In half wave rectification

Current flows in one directions

Only half cycle is used

Current flows in pulses

None of these

168. 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

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

Protons

Neutrons

Extra electrons

Missing electrons

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

None of these

Common base configuration

Common emitter configuration

Common collector configuration

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

Modulus of electricity

Bulk’s modulus

None of these

Young’s modulus

172. A n-p-n transistor conducts when

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

Both collector and emitter are negative with respect to the base

Both collector and emitter are positive with respect to the base

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

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

NAND gates

AND gates

NOT gates

OR gates

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

Superconductor

Insulator

None of these

Semiconductor

175. Which is normal used of transistor?

Rectifier

P-type material

Switching device

Diode

176. 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

177. Arsenic, antimony or phosphorus are impurities of

p-type

may be p-type or n-type

None of these

n-type

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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

Physics Electronics MCQS Online Test

ECAT Physics Electronics Chapter Online Test

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