100+ Basic Electricity Objective Questions and Answers

In this article, we shared the basic electricity objective questions and answers for electrical and electronics engineers.

Basic Electricity Objective Questions

Basic Electricity Objective Questions and Answers

The below list provides all the multiple-choice questions related to basic electricity.

Answers are available at the bottom of the article.

1. The minimum charge on an ion is

A)equal to the charge of an electron
B)equal to the charge of the number of electrons in an atom
C)equal to the atomic number of the atom

2. The electrons revolve around the nucleus with high velocity. The force which acts against the centrifugal force and keeps the electrons in their orbits is

A)electrostatic force of attraction.
B)adhesive force.
C)none of these answers
D)electromagnetic force of attraction.

3. A 100 watt light bulb burns on an average of 10 hours a day for one week. The weekly consumption of energy will be ____unit/s.


4. If a very flexible wire is laid out in the shape of a hair pin with its two ends secured, what shape will the wire tend to assume if a current is passed through it?

C)Straight line.

5. The minimum requirements for causing flow of current are

A)a voltage source, a resistor and a switch.
B)a power source and a bulb.
C)a voltage source, a conductor, an ammeter and a switch.
D)a voltage source and a conductor.

6. For a fixed supply voltage the current flowing through a conductor will increase when its

A)length is increased and x-sectional area is reduced.
B)area of x-section is reduced.
C)length is increased.
D)length is reduced.

7. If Two bulbs of 500W and 200 W rated at 250 V will have resistance ratio as

A)5 : 2
B)2 : 5
C)25 : 4
D)4 : 25

8. Out of the following which is not a poor conductor?

D)Cast iron

9. If I, R and t are the current, resistance and time respectively, then according to Joule’s law heat produced will be proportional to


10. International ohm is defined in terms of the resistance of

A)a cube of copper
B)a cube of carbon
C)a column of mercury
D)the unit length of wire

11. The hot resistance of the bulb’s filament is higher than its cold resistance because the temperature coefficient of the filament is

D)about 2 ohms per degree

12. The thermocouple can not act as

B)A.C. generator

13. The equivalent resistance in series combination is

A)Smaller than the smaller resistance
B)Larger than the smallest resistance
C)Larger than the largest resistance
D)Smaller than the largest resistance

14. In electric kettle water boils in 10 minutes. It is required to boil the boiler in 15 minutes, using the same supply mains

A)none of these answers
B)length of heating element has no effect on heating if water
C)length of heating element should be decreased
D)length of heating element should be increased

15. If the efficiency of a machine is to be high, what should be low?

A)True component of power
C)Input power
D)Ratio of output to input
E)kWh consumed

16. When one leg of the parallel circuit is opened out the total current will

B)become zero

17. An electron charge (e) is revolving in a circular orbit of radius r round a nucleus of charge Ze with speed y. The equivalent current is


18. 1 microvolt is

A)1 x 10-5 ​​V
B)1 x 106 ​​V
C)1 x 10-4 ​​V
D)1 x 10-3 ​​V

19. What is the name of graph between temperature and thermo emf. ?

B)Straight line
D)None of these answers

20. Four 100 W bulbs are connected in parallel across 200 V supply line. If one bulb gets fused

A)all the four bulbs will light.
B)none of these answers
C)rest of the three bulbs will light.
D)no bulb will light.

21. The length of a conductor is halved. Its conductance will be


22. The four bulbs of 40 W each are connected in series with a battery across them, which of the following statement is true?

A)The voltage across each bulb is not same
B)None of these answers
C)The current through each bulb in same
D)The power dissipation in each bulb is not same

23. Through a metallic conductor an electric current is due to drift of

A)Positive and negative ions
B)Free electrons and holes
D)Free electrons

24. 1 angstrom is equal to

A)​10-8 ​mm
B)​​​10-10 ​m
C)​10-14 ​​​m
D)​10-6 ​​​cm

25. A 40 W bulb is connected in series with a room heater. If now 40 W bulb is replaced by 100 W bulb, the heater output will

B)heater will burn out
C)remain same

26. What is converted into heat when current is set up through a conductor?

A)Electric potential
B)None of these answers
C)Electric current
D)Electric energy

27. “The total electric flux through any closed surface surrounding charges is equal to the amount of charges enclosed.” The above statement is based on

A)Gauss’s law.
B)Coulomb’s law.
C)Ampere’s law.
D)Maxwell’s law.

28. The insulation on a current-carrying conductor is provided

A)none of these factors
B)both of to prevent leakage of current & to prevent shock factors
C)to prevent leakage of current
D)to prevent shock

29. Ohm’s law is not applicable to

A)high voltage circuits
B)carbon resistors
C)vacuum tubes
D)circuits with low current densities

30. The rating of a fuse wire is always expressed in


31. Two lamps 100 W and 40 W are connected in series across 230 V (alternating). Which of the following statement is correct?

A)100 W lamp will glow brighter
B)40 W lamp will fuse
C)Both lamps will glow equally bright
D)40 W lamp will glow brighter

32. The Thomson coefficient for lead is

A)More than zero but less than 1
C)Less than zero
D)More than 1

33. The electrical energy required to heat a bucket of water to a certain temperature is 4 kWh. If the heat losses are 20 percent, the energy input is

A)3.2 kWh
B)6 kWh
C)2 kWh
D)5 kWh

34. A field of force can exist only between

A)two ions
B)two atoms
C)two metal particles
D)two molecules

35. Electric current is a quantity

B)Both Vector & Scalar
D)None of these answers

36. The fuse-wire is made of

C)Lead-tin alloy

37. Which method can be used for absolute measurement of resistances?

A)Wheatstone bridge method
B)Ohm’s law method
C)Raleigh method
D)Lorentz method

38. Resistance of 220 V, 100 W lamp will be

A)48.4 ω
B)4840 ω
C)4.84 ω
D)484 ω

39. Which of the following statement is true both for a series and a parallel D.C. circuit?

A)Elements have individual currents
B)Voltages are additive
C)Power are additive
D)Currents are additive

40. The unit of Peltier coefficient is

C)None of these answers

41. Two bulbs 100 W, 250 V, and 200 W, 250 V are connected in series across a 500 V line. Then

A)100 W bulb will be fused
B)200 W bulb will be fused
C)No bulb will be fused
D)Both bulbs will be fused

42. When an electric current passes through a bucket full of water, a lot of bubbling is observed. This suggests that the type of supply is

A)any of these answers
B)none of these answers

43. Three 6 ohm resistors are connected to form a triangle. What is the resistance between any two corners?

A)4 ω
B)8/3 ω
C)3/2 ω
D)6 ω

44. Two heaters, rated at 1000 W, 250 V each are connected in series across a 250 V, 50 Hz ac mains. The total power drawn from the supply would be ____ W.


45. Which of the following has a negative temperature coefficient of resistance?


46. It becomes more difficult to remove

A)first electron from the orbit
B)second electron from the orbit
C)third electron from the orbit
D)any electron from the orbit

47. All of the following are equivalent to watt except

C)​​amperes2 . ohm
D)​​amperes . volt

48. Which of the following does not use heating effect of electric current?

A)Immersion heater.
B)Electric iron.
C)Vacuum cleaner
D)Electric furnace & Electric oven.

49. According to the fuse law, the current-carrying capacity varies as


50. The property of a conductor due to which it passes current is called


51. The electrical conductivity of metals is typically df the order of (in​​)


52. Correct form of Ohm’s law

A)V = IR
B)V = I
C)both V = I and V = IR
D)I = VR

53. Which of the following lamps will have the least resistance at room temperature?

A)60W, 220 V
B)200W, 220 V
C)100 W, 220V
D)25 W, 220V

54. Identify the set in which all the three materials are good conductors of electricity

A)Cu, Si and diamond
B)Cu, Hg and NaCl
C)Cu, Ag, Au
D)Cu, Ge and Hg

55. Bulbs in street Lighting are all connected in


56. Three conductances in parallel have the values G1 = 2000 μ mho, G2 = 3000 μ mho and Gs = 4000 μ mho. The total conductance will be

A)6000 μ mho
B)9000 μ mho
C)10000 μ mho
D)7000 μ mho

57. Water is an excellent solvent because its molecules are

D)High polar

58. How many 200 W/220 V incandescent lamps connected in series would consume the same total power as a single 100 W/220 V incandescent lamp?

A)not possible.

59. Three 60W bulbs are in parallel across the 60V power line. If one bulb burns open

A)all three bulbs will light
B)the other two bulbs will light
C)rest of the two bulbs will not light
D)there will be heavy current in the main line

60. The ratio of mass of proton to that of electron is nearly


61. Electric current passing through the circuit produces

A)all of these effects
B)luminous effect
C)magnetic effect
D)thermal effect
E)chemical effect

62. The condition for the validity of Ohm’ s law is that the

A)current should be proportional to voltage.
B)temperature should remain constant.
C)resistance must be wire wound type.
D)all of these answers

63. When electric current passes through a metallic conductor, its temperature rises. This is due to

A)mutual collisions between metal atoms
B)mutual collisions between conducting electrons
C)the release of conduction electrons from parent atoms
D)collisions between conduction electrons and atoms

64. Two wires A and B of the same material and length l and 2l have radius r and 2r respectively. The ratio of their specific resistance will be

A)1 : 2
B)1 : 8
C)1 : 1
D)1 : 4

65. The draft velocity of electrons is

A)very small in comparison to speed of light.
B)almost equal to speed of light
C)equal to speed of light.
D)larger than speed of light.

66. Copper wire of certain length and resistance is drawn out to three times its length without change in volume, the new resistance of wire becomes

B)1/9 times
C)9 times
D)3 times

67. Ohm’s law is not applicable to

A)high currents
B)D.C. circuits
C)small resistors

68. Ohm’s law is applicable to

A)arc lamps.
B)electrolytes & carbon resistors.
C)semiconductors & vacuum tubes.
D)none of these answers

69. The maximum current rating for a 10 kω, 0.5 W resistor is

A)0.707 mA
B)7.07 mA
C)28.28 mA
D)14.14 mA

70. Which of the following statement is correct?

A)A semi-conductor is a material whose conductivity is same as between that of a conductor and an insulator
B)A semi-conductor is one which conducts only half of the applied voltage
C)A semi-conductor is a material which has conductivity having average value of conductivity of metal and insulator
D)A semi-conductor is a material made of alternate layers of conducting material and insulator

71. Which of the following could be th value of resistivity of copper?

A)1.72 x​​ 10-4 ω-m
B)1.72 x​​ 10-5 ω-m
C)1.72 x​​ 10-6 ω-m
D)1.72 x​​ 10-7 ω-m

72. An isolated conducting sphere is given a positive charge. It’s mass

A)Remain the same
B)Mass is not involved

73. Whether circuit may be AC. or D.C. one, following is most effective in reducing the magnitude of the current.


74. Current velocity through a copper conductor is

A)independent of current strength.
B)nearly 3 X 109 ​​m/s.
C)of the order of a few micro m/s.
D)the same as propagation velocity of electric energy.

75. In gases the flow of current is due to

A)positive ions only
B)electrons and positive ions
C)electrons, positive ions and negative ions
D)electrons only

76. The thermo-electric power at the neutral temperature is

A)None of these answers

77. Electric pressure is also called


78. A 200 W, 230 V lamp is connected across 115 V supply. The lamp will draw power

A)slightly more than 50W.
B)slightly less than 50W.
C)exactly 50W.
D)exactly 100 W.

79. Three identical resistors are first connected in parallel and then in series. The resultant resistance of the first combination to the second will be

A)1/9 times
B)3 times
C)9 times
D)1/3 times

80. When a voltage of one volt is applied, a circuit allows one micro ampere current to flow through it. The conductance of the circuit is

A)1 μ-mho
B)1 milli-mho
C)none of these answers
D)106 mho

81. The electric current in a liquid is due to the flow of

A)Electrons and positive ions both
B)Negative and positive ions both
C)Electrons only
D)Positive ions only

82. The draft velocity of electrons is

A)very small as compared to speed of light
B)greater than speed of light
C)almost equal to speed of light
D)equal to speed of light

83. The flow of current in solids is due to

A)electrons and ions

84. What is thermoelectric power? It is the rate of change of thermo emf with

D)None of these answers

85. The quantity of electricity analogous to friction in linear mechanical motion is


86. Which of the following statements is incorrect?

A)Resistance is a passive element.
B)Voltage source is an active element.
C)Current source is a passive element.
D)Inductor is a passive element.

87. A substance whose molecules consist of dissimilar atoms is called


88. A glass rod when rubbed with silk cloth is charged because

A)it gives away positive charge
B)it takes in proton
C)its atoms are removed
D)it gives away electrons

89. A 500 W, 220 V bulb is supplied with 110V. Power consumption by the bulb will be

A)slightly less than 125 W
B)250 W
C)exactly 125 W
D)slightly greater than 125 W

90. When subjected to a transverse electric field, cathode rays move

A)Down the potential gradient
B)Up the potential gradient
C)Along a circular path
D)Along a hyperbolic path

91. Which of the following can have a negative temperature coefficient?

B)Liquid metals
C)Metallic alloys
D)Compounds of silver

92. Which is the best conductor of electricity?


93. For testing appliances, the wattage of the test lamp should be

A)very low
B)any value

94. When there is an electric current through a conducting wire along its length, then an electric field must exist.

A)Inside the wire but parallel to it
B)Inside the wire but normal to it
C)Outside the wire but parallel to it
D)Outside the wire but normal to it

95. Resistance of a tungsten lamp ____ as applied voltage increases

A)remains same
C)none of these answers

96. Sparking occurs when a load is switched off because the circuit has high


97. Two incandescent light bulbs of 40 W and 60 W rating are connected in series across the mains. Then

A)the bulbs together consume 100 W.
B)the 40 W bulb glows brighter.
C)the bulbs together consume 50 W.
D)the 60 W bulb glows brighter.

98. The thermal speed of electrons is of the order of

A)​​10-3 m/s
B)​​3 x ​​108 m/s
C)​​​​106 m/s
D)​​​​1 m/s

99. One newton metre is same as

A)five joules
B)one joule second
C)one joule
D)one watt

100. A region surrounding a stationary electric dipole has

A)Electric field only
B)No electric and magnetic fields
C)Magnetic field only
D)Both electric and magnetic fields

101. In the case of direct current

A)magnitude of current changes with time
B)magnitude and direction of current remains constant
C)magnitude of current remains constant
D)magnitude and direction of current changes with time

102. The substances which have a large number of free electrons and offer a low resistance are called


103. The thickness of insulation provided on the conductor depends on

A)both the magnitude of voltage on the conductor and the magnitude of current flowing through it
B)the magnitude of voltage on the conductor
C)the magnitude of current flowing through it
D)none of these answers

104. Switching of a lamp in house produces noise in the radio. This is because switching operation produces

A)both mechanical noise and arc between contacts
B)arcs across separating contacts
C)none of these answers
D)mechanical noise of high intensity

105. The resistance of human body is around

A)25 ohms
B)5 ohms
C)250 ohms
D)1000 ohms

106. In a lamp load when more than one lamp are switched on the total resistance of the load

B)remains same
D)none of these answers

107. When current flows through heater coil it glows but supply wiring does not glow because

A)resistance of heater coil is more than the supply wires
B)supply wires are made of superior material
C)current through supply line flows at slower speed
D)supply wiring is covered with insulation layer

108. As the temperature of hot junction increases, the thermo emf :

A)May increase or decrease
B)Always increases
C)Neither increase nor decrease
D)Always decreases

109. Pure metals generally have

A)high conductivity and large temperature coefficient.
B)low conductivity and zero temperature coefficient.
C)low conductivity and high temperature coefficient.
D)high conductivity and low temperature coefficient.

110. A steady current flows in a metallic conductor of non-uniform cross-section. Out of the following physical quantities, the one which remains constant is

A)Electric field
C)Drift speed

111. The conductivity of a super-conductor is

A)Very large
B)Very small

112. The number of electrons in the outermost orbit of carbon atom is


113. An electrical lamp consumes 100 W of power. If the supply voltage is 220V the energy consumed in 30 minutes is

B)0.05 kWh
C)0.005 kWh

114. Which of the following is not reversible?

A)Thomson’s effect
B)Peltier effect
C)Joule’s effect
D)Seebeck effect

115. Which of the following characteristics of electrons determines the current in a conductor?

A)Drift velocity alone
B)Both Drift velocity alone & Thermal velocity alone
C)None of these answers
D)Thermal velocity alone

116. While using electricity and paying the electric bills one pay for

A)Electric energy
B)Electric power
C)Electric current
D)Electric charge

117. The flow of electric current in a conductor is due to flow of

B)electrons and ions.
C)charged particles.

118. What is the nature of graph between temperature and thermoelectric power ?

A)None of these answers
D)Straight line

119. Which of the following relation is incorrect?

A)P =​​ V/R2
B)P = VI
C)P = IR
D)P =​​ V2/R

120. If a parallel circuit is opened in the main line, the current

A)increases in the branch of the lowest resistance
B)is zero in all branches
C)is zero in the highest resistive branch
D)increases in each branch

121. Seebeck effect is inverse of

A)None of these answers
B)Thomson’s effect
C)Joule’s effect
D)Peltier effect

122. All good conductors have high

B)thermal conductivity

123. When an electric current flows through a conductor, its temperature rises. This is because of

A)release of conduction electrons from parent atoms.
B)mutual collisions between conducting electrons.
C)mutual collisions between metal atoms.
D)collisions between conduction electrons and atoms.

124. Which of the following is not equivalent to watts?

A)​​ amperes2 x ohm
B)​​amperes x volt
D)​​joules per second

125. An electric current is the

A)pressure difference between two poles.
B)random movement of electrons in a conductor
C)the power that causes drift of electrons.
D)movement of free electrons predominately in one direction.

126. Resistance of carbon filament lamp ____ as the applied voltage increases

A)none of these answers
C)remains same

127. When the resistance element of a heater fuses and then we reconnect it after removing a portion of it, the power of the heater will

A)none of these answers
B)remain constant

128. A nichrome wire used as a heater coil has a resistance of 2 ω/m. For a heater of 1 kW at 200 V, the length of wire required will be

A)60 m
B)20 m
C)40 m
D)80 m

129. The dimensions of the emf of a source of current are that of

C)Electric field

130. Current velocity through a copper conductor is

A)nearly 3 x​​ 109 m/s
B)the same as propagation velocity of electric energy
C)of the order of a few μs/m
D)independent of current strength

131. The electric field at a point on the equatorial line of a dipole, and the direction of the dipole moment

A)Are not related
B)Will be perpendicular
C)Will be parallel
D)Will be in opposite direction

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