# Current Electricity Multiple choice Questions & Answers

Posted On:February 4, 2019, Posted By: Latest Interview Questions, Views: 1198, Rating :     ## Best Current Electricity Objective Questions and Answers

Dear Readers, Welcome to Current Electricity Objective Questions have been designed specially to get you acquainted with the nature of questions you may encounter during your Job interview for the subject of Current Electricity MCQs. These objective type Current Electricity questions are very important for campus placement test and job interviews. As per my experience good interviewers hardly plan to ask any particular question during your Job interview and these model questions are asked in the online technical test and interview of many IT companies.

### 1. The S.I. unit of power is

(a) henry

(b) coulomb

(c) watt

(d) watt-hour

Ans: c (a) resistance

(b) power

(c) voltage

(d) energy

Ans: c

### 3. The substances whfch have a large number of free electrons and offer a low resistance are called

(a)     insulators

(b)     inductors

(c) semi-conductors

(d) conductors

Ans: d

(a) Cast iron

(b) Copper

(c) Carbon

(d) Tungsten

Ans: b

(a) Copper

(b) Gold

(c) Silver

(d) Paper

Ans: d

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

(a) resistance

(b) reluctance

(c) conductance

(d) inductance

Ans: c

(a) resistance

(b) inductance

(c) reluctance

(d) capacitance

Ans: a

### 8. The resistance of a conductor varies inversely as

(a) length

(6) area of cross-section

(c) temperature

(d) resistivity

Ans: b

### 9. With rise in temperature the resistance of pure metals

(a) increases

(b) decreases

(c) first increases and then decreases

(d) remains constant

Ans: a

### 10. With rise in temperature the resistance of semi-conductors

(a)     decreases

(b)     increases

(c) first increases and then decreases

(d) remains constant

Ans: a

### 11. The resistance of a copper wire 200 m long is 21 Q. If its thickness (diameter) is 0.44 mm, its specific resistance is around

(a) 1.2 x 10~8 Q-m

(b) 1.4 x 10~8 Q-m

(c) 1.6 x 10""8 Q-m

(d) 1.8 x 10"8 Q-m

Ans: c

(a) 5 ohms

(b) 10 ohms

(c) 15 ohms

(d) 55 ohms

Ans:

(a) voltmeter

(b) rheostat

(c) wattmeter

(d) galvanometer

Ans: d

(a) 33 V

(b) 66 v

(c) 80 V

(d) 132 V

Ans: b

(a) 400 Q

(b) 600 Q

(c) 800 Q

(d) 1000 Q

Ans: c

(a) 18 Q

(b) 36 Q

(c) 48 Q

(d) 64 Q

Ans: b

(a) 1 Q

(b) 2 Q

(c) 3 Q

(d) 4 Q

Ans: d

### 18. A current of 16 amperes divides between two branches in parallel of resistances 8 ohms and 12 ohms respectively. The current in each branch is

(a) 6.4 A, 6.9 A

(b) 6.4 A, 9.6 A

(c) 4.6 A, 6.9 A

(d) 4.6 A, 9.6 A

Ans: b

### 19. Current velocity through a copper conductor is

(a) the same as propagation velocity of electric energy

(b) independent of current strength

(c) of the order of a few ^.s/m

(d) nearly 3 x 108 m/s

Ans: c

(a) Manganin

(b) Porcelain

(c) Carbon

(d) Copper

Ans: a

### 21. You have to replace 1500 Q resistor in radio. You have no 1500 Q resistor but have several 1000 Q ones which you would connect

(a) two in parallel

(b) two in parallel and one in series

(c) three in parallel

(d) three in series

Ans: b

### 22. Two resistors are said to be connected in series when

(a) same current passes in turn through both

(b) both carry the same value of current

(c) total current equals the sum of branch currents

(d) sum of IR drops equals the applied e.m.f.

Ans: a

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

(a) Elements have individual currents

(b) Currents are additive

(c) Voltages are additive

(d) Power are additive

Ans: d

(a) Copper

(b) Aluminum

(c) Carbon

(d) Brass

Ans: c

### 25. Ohm's law is not applicable to

(a) vacuum tubes

(b) carbon resistors

(c) high voltage circuits

(d) circuits with low current densities

Ans: a

(a) Iron

(b) Silver

(c) Copper

(d) Carbon

Ans: b

### 27. For which of the following 'ampere second' could be the unit ?

(a) Reluctance

(b) Charge

(c) Power

(d) Energy

Ans: b

### 28. All of the following are equivalent to watt except

(a) (amperes)  ohm

(b) joules/sec.

(c)     amperes x volts

(d) amperes/volt

Ans: d

### 29. A resistance having rating 10 ohms, 10W is likely to be a

(a)     metallic resistor

(b)     carbon resistor

(c) wire wound resistor

(d) variable resistor

Ans: c

### 30. Which one of the following does not have negative temperature co-efficient ?

(a) Aluminium

(b) Paper

(c) Rubber

(d) Mica

Ans: a

### 31. Varistors are

(a)     insulators

(6)     non-linear resistors

(c) carbon resistors

(d) resistors with zero temperature coefficient

Ans: b

### 32. Insulating materials have the function of

(a)     preventing a short circuit between conducting wires

(b)     preventing an open circuit between the voltage source and the load

(c) conducting very large currents

(d) storing very high currents

Ans: b

### 33. The rating of a fuse wire is always expressed in

(a) ampere-hours

(b) ampere-volts

(c) kWh

(d) amperes

Ans: d

### 34. The minimum charge on an ion is

(a) equal to the atomic number of the atom

(b) equal to the charge of an electron

(c) equal to the charge of the number of electrons in an atom (#) zero

Ans: b

### 35. In a series circuit with unequal resistances

(a) the highest resistance has the most of the current through it

(b) the  lowest resistance has the highest voltage drop

(c) the  lowest resistance has the highest current

(d) the highest resistance has the highest voltage drop

Ans: d

(a) carbon

(b) aluminium

(c) tungsten

(d) nickel

Ans: c

(a) 2 watts

(b) 4 watts

(c) 6 watts

(d) 8 watts

Ans: c

### 38. Which of the following statement is true?

(a) A galvanometer with low resistance in parallel is a voltmeter

(b) A galvanometer with high resis¬tance in parallel is a voltmeter

(c) A galvanometer with low resistance in series is an ammeter

(d)     A galvanometer with high resis¬tance in series is an ammeter

Ans: c

### 39. The resistance of a few metres of wire conductor in closed electrical circuit is

(a) practically zero

(b) low

(c) high

(d) very high

Ans: a

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

(a) increases in the branch of the lowest resistance

(b) increases in each branch

(c) is zero in all branches

(d) is zero in the highest resistive branch

Ans: c

(a) 0.4 ohm

(b) 0.6 ohm

(c) 0.8 ohm

(d) 1.0 ohm

Ans: a

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

(a) there will be heavy current in the main line

(b) rest of the two bulbs will not light

(c) all three bulbs will light

(d) the other two bulbs will light

Ans: d

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

(a) The current through each bulb in same

(b) The voltage across each bulb is not same

(c) The power dissipation in each bulb is not same

(d) None of the above

Ans: a

### 44. Two resistances R1 and R2 are connected in series across the voltage source where R2>R1. The largest drop will be across

(a) R2

(b) R1

(c) either R1 or R2

(d) none of them

Ans: a

(a) 5 joules

(b) 10 joules

(c) 15 joules

(d) 20 joules

Ans:

### 46. A closed switch has a resistance of

(a) zero

(b) about 50 ohms

(c) about 500 ohms

(d) infinity

Ans: a

### 47. The hot resistance of the bulb's filament is higher than its cold resistance because the temperature co-efficient of the filament is

(a)     zero

(b)     negative

(c) positive

(d) about 2 ohms per degree

Ans: c

(a) reactance

(b) capacitance

(c) impedance

(d) resistance

Ans:

### 49. The insulation on a current carrying conductor is provided

(a)     to prevent leakage of current

(b)     to prevent shock

(c) both of above factors

(d) none of above factors

Ans: c

### 50. The thickness of insulation provided on the conductor depends on

(a) the magnitude of voltage on the con-ductor

(b) the magnitude of current flowing through it

(c) both (a) and (b)

(d) none of the above

Ans: a

(a) Voltage

(b) Current

(c) Power

(d) Resistance

Ans: b

### 52. 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

(a)     decrease

(b)     increase

(c) remain same

(d) heater will burn out

Ans: b

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

(a)     length of heating element should be decreased

(b)     length of heating element should be increased

(c) length of heating element has no effect on heating if water

(d) none of the above

Ans: a

### 54. An electric filament bulb can be worked from

(a) D.C. supply only

(b) A.C. supply only

(c)     Battery supply only

(d)     All above

Ans: d

### 55. Resistance of a tungsten lamp as applied voltage increases

(a)     decreases

(b)     increases

(c) remains same

(d) none of the above

Ans: b

### 56. Electric current passing through the circuit produces

(a)     magnetic effect

(b)     luminous effect

(c)     thermal effect

(d)     chemical effect

(e) all above effects

Ans: c

### 57. Resistance of a material always decreases if

(a)     temperature of material is decreased

(6)     temperature of material is increased

(c) number of free electrons available become more

(d) none of the above is correct

Ans: c

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

(a)     Input power

(b)     Losses

(c) True component of power

(d) kWh consumed

(e) Ratio of output to input

Ans: b

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

(a)     collisions between conduction electrons and atoms

(b) the release of conduction electrons from parent atoms

(c) mutual collisions between metal atoms

(d) mutual collisions between conducting electrons

Ans: a

(a) 4 : 25

(b) 25 : 4

(c) 2 : 5

(d) 5 : 2

Ans: c

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

(a) it takes in proton

(b) its atoms are removed

(c) it gives away electrons

(d) it gives away positive charge

Ans: c

(a) Reactor

(b) Capacitor

(c) Inductor

(d) Resistor

Ans: d

### 63. It becomes more difficult to remove

(a) any electron from the orbit

(6) first electron from the orbit

(c) second electron from the orbit

(d) third electron from the orbit

Ans: d

(a) reduce

(b) increase

(c) decrease

(d) become zero

Ans: c

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

(a)     increases

(b)     decreases

(c) remains same

(d) none of the above

Ans: b

### 66. 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 glow brighter

(c) Both lamps will glow equally bright

(d) 40 W lamp will fuse

Ans: b

(a) 4.84 Q

(b) 48.4 Q

(c) 484 ft

(d) 4840 Q

Ans: c

### 68. In the case of direct current

(a) magnitude and direction of current remains constant

(b) magnitude and direction of current changes with time

(c) magnitude of current changes with time

(d) magnitude of current remains con¬stant

Ans: a

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

(a)     A.C.

(b)     D.C.

(c) any of above two

(d) none of the above

Ans: b

### 70. Resistance of carbon filament lamp as the applied voltage increases.

(a)     increases

(b)     decreases

(c) remains same

(d) none of the above

Ans: b

### 71. Bulbs in street lighting are all connected in

(a) parallel

(b) series

(c) series-parallel

(d) end-to-end

Ans: a

(a) very low

(b) low

(c) high

(d) any value

Ans: c

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

(a)     arcs across separating contacts

(b)     mechanical noise of high intensity

(c) both mechanical noise and arc be¬tween contacts

(d) none of the above

Ans: a

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

(a) resistance

(b) inductance

(c) capacitance

(d) impedance

Ans: b

(a) 1/9 times

(b) 3 times

(e) 9 times

(d) unchanged

Ans: c

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

(a)     decrease

(b)     increase

(c) remain constant

(d) none of the above

Ans: b

### 77. A field of force can exist only between

(a)     two molecules

(b)     two ions

(c) two atoms

(d) two metal particles

Ans: b

### 78. A substance whose molecules consist of dissimilar atoms is called

(a) semi-conductor

(b) super-conducto

(c) compound

(d) insulator

Ans: c

### 79. International ohm is defined in terms of the resistance of

(a) a column of mercury

(b) a cube of carbon

(c) a cube of copper

(d) the unit length of wire

Ans: a

(a) 9 times

(b) 1/9 times

(c) 1/3 times

(d) 3 times

Ans: b

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

(a) Lorentz method

(b) Releigh method

(c) Ohm's law method

(d) Wheatstone bridge method

Ans: d

(a) 3/2 Q

(b  6 Q

(c) 4 Q

(d) 8/3 Q

Ans: c

### 93. Ohm's law is not applicable to

(a) semi-conductors

(b) D.C. circuits

(c) small resistors

(d) high currents

Ans: a

(a) 160 ohms

(b) 80 ohms

(c) 20 ohms

(d) 10 ohms

Ans: d

(a) 80 m

(b) 60 m

(c) 40 m

(d) 20 m

Ans: a

### 96. Temperature co-efficient of resistance is expressed in terms of

(a) ohms/°C

(b) mhos/ohm°C

(e) ohms/ohm°C

(d) mhos/°C

Ans: c

(a) Zinc

(b) Lead

(c) Mercury

(d) Copper

Ans:

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

(a) current through supply line flows at slower speed

(b) supply wiring is covered with in¬sulation layer

(c) resistance of heater coil is more than the supply wires

(d) supply wires are made of superior material

Ans: c

### 99. The condition for the validity under Ohm's law is that

(a) resistance must be uniform

(b) current should be proportional to the size of the resistance

(c) resistance must be wire wound type

(d) temperature at positive end should be more than the temperature at negative end

Ans: a

### 100. Which of the following statement is correct ?

(a) A semi-conductor is a material whose conductivity is same as be¬tween that of a conductor and an insulator

(b) A semi-conductor is a material which has conductivity having average value of conductivity of metal and insulator

(c) A semi-conductor is one which con¬ducts only half of the applied voltage

(d)     A semi-conductor is a material made of alternate layers of conducting material and insulator

Ans: a

### 101. A rheostat differs from potentiometer in the respect that it

(a)     has lower wantage rating

(b)     has higher wattage rating

(c) has large number of turns

(d) offers large number of tappings

Ans: b

(a) 50%

(b) 60%

(c) 100%

(d) 150%

Ans: a

### 103. An open resistor, when checked with an ohm-meter reads

(a)     zero

(b)     infinite

(c) high but within tolerance

(d) low but not zero

Ans: b

### 104. are the materials having electrical conductivity much less than most of the metals but much greater than that of typical insulators.

(a)     Varistors

(b)     Thermistor

(c) Semi-conductors

(d) Variable resistors

Ans: c

### 105. All good conductors have high

(a)     conductance

(b)     resistance

(c) reluctance

(d) thermal conductivity

Ans: a

### 106. Voltage dependent resistors are usually made from

(a) charcoal

(b) silicon carbide

(c) nichrome

(d) graphite

Ans: c

### 107. Voltage dependent resistors are used

(a)     for inductive circuits

(6)     to supress surges

(c) as heating elements

(d) as current stabilizers

Ans: b

(a) 1840

(b) 1840

(c) 30

(d) 4

Ans: a

(a) 3

(b) 4

(c) 6

(d) 7

Ans: b

(a) 10 W

(b) 20 W

(c) 40 W

(d) 60 W

Ans: d

### 111. A thermistor has

(a) positive temperature coefficient

(b) negative temperature coefficient

(c) zero temperature coefficient

(d) variable temperature coefficient

Ans: c

(a) I2Rt

(b) I2Rf

(c) I2R2t

(d) I2R2t*

Ans: a

### 113. Nichrome wire is an alloy of

(a) lead and zinc

(b) chromium and vanadium

(c) nickel and chromium

(d) copper and silver

Ans: c

### 114. When a voltage of one volt is applied, a circuit allows one microampere current to flow through it. The conductance of the circuit is

(a)     1 n-mho

(b)     106 mho

(c) 1 milli-mho

(d) none of the above

Ans: a

### 115. Which of the following can have negative temperature coefficient ?

(a) Compounds of silver

(6) Liquid metals

(c) Metallic alloys

(d) Electrolytes

Ans: d

### 116. Conductance : mho ::

(a)     resistance : ohm

(b)     capacitance : henry

(c) inductance : farad

(d) lumen : steradian

Ans: a

(a) 10-8 mm

(6) 10"6 cm

(c) 10"10 m

(d) 10~14 m

Ans: c

### 118. One newton metre is same as

(a) one watt

(b) one joule

(c) five joules

(d) one joule second

Ans: b