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Q 1. Which of the following statement is true both for a series and a parallel D.C. circuit?

DRex Electronics

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

Answer: Option D

Q 2. 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

Answer: Option B

Q 3. The hot resistance of the bulb’s filament is higher than its cold resistance because the temperature coefficient of the filament is

(A) Zero
(B) Negative
(C) Positive
(D) About 2 ohms per degree

Answer: Option C

Q 4. Resistance of a material always decreases if

(A) Temperature of material is decreased
(B) Temperature of material is increased
(C) Number of free electrons available becomes more
(D) None of the above is correct

Answer: Option C

 Q 5. 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 constant

Answer: Option A

Q 6. Two copper conductors have equal length. The cross-sectional area of one conductor is four times that of the other. If the conductor having smaller cross-sectional area has a resistance of 40 ohms the resistance of other conductor will be

(A) 160 ohms
(B) 80 ohms
(C) 20 ohms
(D) 10 ohms

Answer: Option D

Q 7. Which of the following statement is correct?

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

Answer: Option A

Q 8. Which of the following can have negative temperature coefficient?

(A) Compounds of silver
(B) Liquid metals
(C) Metallic alloys
(D) Electrolytes

Answer: Option D

Q 9. An instrument which detects electric current is known as

(A) Voltmeter
(B) Rheostat
(C) Wattmeter
(D) Galvanometer

Answer: Option D

Q 10. Four wires of same material, the same cross-sectional area and the same length when connected in parallel give a resistance of 0.25 Q. If the same four wires are connected is series the effective resistance will be

(A) 1 Q
(B) 2 Q
(C) 3 Q
(D) 4 Q

Answer: Option D

Q 11. Sparking occurs when a load is switched off because the circuit has high

(A) Resistance
(B) Inductance
(C) Capacitance
(D) Impedance

Answer: Option B

Q 12. 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

Answer: Option A

Q 13. An open resistor, when checked with an ohmmeter reads

(A) Zero
(B) Infinite
(C) High but within tolerance
(D) Low but not zero

Answer: Option B

Q 14. The number of electrons in the outer most orbit of carbon atom is

(A) 3
(B) 4
(C) 6
(D) 7

Answer: Option B

Q 15. A field of force can exist only between

(A) Two molecules
(B) Two ions
(C) Two atoms
(D) Two metal particles

Answer: Option B

Q 16. 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.

Answer: Option A

Q 17. Varistors are

(A) Insulators
(B) Nonlinear resistors
(C) Carbon resistors
(D) Resistors with zero temperature coefficients

Answer: Option B

Q 18. 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

Answer: Option C

Q 19. In an electric kettle water boils in 10 m 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

Answer: Option A

Q 20. It becomes more difficult to remove

(A) Any electron from the orbit
(B) First electron from the orbit
(C) Second electron from the orbit
(D) Third electron from the orbit

Answer: Option D

Q 21. 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 between contacts
(D) None of the above

Answer: Option A

Q 22. Ohm’s law is not applicable to

(A) Semiconductors
(B) D.C. circuits
(C) Small resistors
(D) High currents

Answer: Option A

Q 23. 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) Semiconductors
(D) Variable resistors

Answer: Option C

Q 24. A thermistor has

(A) Positive temperature coefficient
(B) Negative temperature coefficient
(C) Zero temperature coefficient
(D) Variable temperature coefficient

Answer: Option C

Q 25. The substances which have a large number of free electrons and offer a low resistance are called

(A) Insulators
(B) Inductors
(C) Semiconductors
(D) Conductors

Answer: Option D

Q 26. A light bulb draws 300 mA when the voltage across it is 240 V. The resistance of the light bulb is

(A) 400 Q
(B) 600 Q
(C) 800 Q
(D) 1000 Q

Answer: Option C

Q 27. For which of the following ‘ampere second’ could be the unit?

(A) Reluctance
(B) Charge
(C) Power
(D) Energy

Answer: Option B

Q 28. 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

Answer: Option D

Q 29. Two resistances Rl and Ri are connected in series across the voltage source where Rl > Ri. The largest drop will be across

(A) Rl
(B) Ri
(C) Either Rl or Ri
(D) None of them

Answer: Option A

Q 30. Electric current passing through the circuit produces

(A) Magnetic effect
(B) Luminous effect
(C) Thermal effect
(D) Chemical effect

Answer: Option C

Q 31. 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

Answer: Option B

Q 32. A substance whose molecules consist of dissimilar atoms is called

(A) Semiconductor
(B) Super-conductor
(C) Compound
(D) Insulator

Answer: Option C

Q 33. A rheostat differs from potentiometer in the respect that it

(A) Has lower wattage rating
(B) Has higher wattage rating
(C) Has large number of turns
(D) Offers large number of tapping

Answer: Option B

Q 34. The ratio of mass of proton to that of electron is nearly

(A) 1837
(B) 1840
(C) 30
(D) 4

Answer: Option A

Q 35. Which of the following quantities remain the same in all parts of a series circuit?

(A) Voltage
(B) Current
(C) Power
(D) Resistance

Answer: Option B

Q 36. 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

Answer: Option A

Q 37. 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

Answer: Option B

Q 38. 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

Answer: Option B

Q 39. Temperature coefficient of resistance is expressed in terms of

(A) ohms/°C
(B) mhos/ohm°C
(C) ohms/ohm°C
(D) mhos/°C

Answer: Option C

Q 40. Voltage dependent resistors are usually made from

(A) Charcoal
(B) Silicon carbide
(C) Nichrome
(D) Graphite

Answer: Option C

Q 41. Conductance: mho ::

(A) Resistance : ohm
(B) Capacitance : Henry
(C) Inductance : farad
(D) lumen : steradian

Answer: Option A

Q 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

Answer: Option D

Q 43. The S.I. unit of power is

(A) Henry
(B) Coulomb
(C) Watt
(D) Watt-hour

Answer: Option C

Q 44. The resistance of a conductor varies inversely as

(A) Length
(B) Area of cross-section
(C) Temperature
(D) Resistivity

Answer: Option B

Q 45. In a circuit a 33 Q resistor carries a current of 2 A. The voltage across the resistor is

(A) 33 V
(B) 66 V
(C) 80 V
(D) 132 V

Answer: Option B

Q 46. Which of the following materials has a negative temperature coefficient of resistance?

(A) Copper
(B) Aluminum
(C) Carbon
(D) Brass

Answer: Option C

Q 47. A resistance having rating 10 ohms, 10 W is likely to be a

(A) Metallic resistor
(B) Carbon resistor
(C) Wire wound resistor
(D) Variable resistor

Answer: Option C

Q 48. The resistance of a few meters of wire conductor in closed electrical circuit is

(A) Practically zero
(B) Low
(C) High
(D) Very high

Answer: Option A

Q 49. 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

Answer: Option B

Q 50. 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

Answer: Option C

Q 51. Bulbs in street lighting are all connected in

(A) Parallel
(B) Series
(C) Series-parallel
(D) End-to-end

Answer: Option A

Q 52. Which method can be used for absolute measurement of resistances?

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

Answer: Option D

Q 53. All good conductors have high

(A) Conductance
(B) Resistance
(C) Reluctance
(D) Thermal conductivity

Answer: Option A

Q 54. 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 n-mho
(B) 106 mho
(C) 1 milli-mho
(D) None of the above

Answer: Option A

Q 55. One Newton meter is same as

(A) One watt
(B) One joule
(C) Five joules
(D) One joule second

Answer: Option B

Q 56. 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

Answer: Option A

Q 57. 1 angstrom is equal to

(A) 108 mm
(B) 10-6 cm
(C) 10-10 m
(D) 10-14 m

Answer: Option C

Q 58. Out of the following which is an insulating material?

(A) Copper
(B) Gold
(C) Silver
(D) Paper

Answer: Option D

Q 59. 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

Answer: Option B

Q 60. All of the following are equivalent to watt except

(A) (Amperes) ohm
(B) Joules/sec.
(C) Amperes × volts
(D) Amperes/volt

Answer: Option D

Q 61. Which of the following statement is true?

(A) A galvanometer with low resistance in parallel is a voltmeter
(B) A galvanometer with high resistance in parallel is a voltmeter
(C) A galvanometer with low resistance in series is an ammeter
(D) A galvanometer with high resistance in series is an ammeter

Answer: Option C

Q 62. 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

Answer: Option D

Q 63. 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

Answer: Option B

Q 64. 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

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

Answer: Option C

Q 65. The weight of an aluminium conductor as compared to a copper conductor of identical cross-section, for the same electrical resistance, is

(A) 50 %
(B) 60 %
(C) 100 %
(D) 150 %

Answer: Option A

Q 66. Voltage dependent resistors are used

(A) For inductive circuits
(B) To suppress surges
(C) As heating elements
(D) As current stabilizers

Answer: Option B

Q 67. If I, R and t are the current, resistance and time respectively, then according to Joule’s law heat produced will be proportional to

(A) I2Rt
(B) I2Rf
(C) I2R2t
(D) I2R2t2

Answer: Option A

Q 68. Which one of the following does not have negative temperature coefficient?

(A) Aluminium
(B) Paper
(C) Rubber
(D) Mica

Answer: Option A

Q 69. Electric pressure is also called

(A) Resistance
(B) Power
(C) Voltage
(D) Energy

Answer: Option C

Q 70. With rise in temperature the resistance of semiconductors

(A) Decreases
(B) Increases
(C) First increases and then decreases
(D) Remains constant

Answer: Option A

Q 71. Ohm’s law is not applicable to

(A) Vacuum tubes
(B) Carbon resistors
(C) High voltage circuits
(D) Circuits with low current densities

Answer: Option A

Q 72. The four bulbs of 40 W each are connected in series swift 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

Answer: Option A

Q 73. 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

Answer: Option B

Q 74. Resistance of 220 V, 100 W lamp will be

(A) 4.84 Q
(B) 48.4 Q
(C) 484 ft
(D) 4840 Q

Answer: Option C

Q 75. Three 6 ohm resistors are connected to form a triangle. What is the resistance between any two corners?

(A) 3/2 Q
(B) 6 Q
(C) 4 Q
(D) 8/3 Q

Answer: Option C

Q 76. 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 insulation layer
(C) Resistance of heater coil is more than the supply wires
(D) Supply wires are made of superior material

Answer: Option C

Q 77. The filament of an electric bulb is made of

(A) Carbon
(B) Aluminium
(C) Tungsten
(D) Nickel

Answer: Option C

Q 78. Out of the following which is not a poor conductor?

(A) Cast iron
(B) Copper
(C) Carbon
(D) Tungsten

Answer: Option B

Q 79. The resistance of a parallel circuit consisting of two branches is 12 ohms. If the resistance of one branch is 18 ohms, what is the resistance of the other?

(A) 18 Q
(B) 36 Q
(C) 48 Q
(D) 64 Q

Answer: Option B

Q 80. 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
(D) None of these

Answer: Option B

Q 81. Whether circuit may be AC. or D.C. one, following is most effective in reducing the magnitude of the current.

(A) Reactor
(B) Capacitor
(C) Inductor
(D) Resistor

Answer: Option D

Q 82. 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) 9 times
(B) 1/9 times
(C) 1/3 times
(D) 3 times

Answer: Option B

Q 83. Nichrome wire is an alloy of

(A) Lead and zinc
(B) Chromium and vanadium
(C) Nickel and chromium
(D) Copper and silver

Answer: Option C

Q 84. The property of a conductor due to which it passes current is called

(A) Resistance
(B) Reluctance
(C) Conductance
(D) Inductance

Answer: Option C

Q 85. Which is the best conductor of electricity?

(A) Iron
(B) Silver
(C) Copper
(D) Carbon

Answer: Option B

Q 86. The thickness of insulation provided on the conductor depends on

(A) The magnitude of voltage on the conductor
(B) The magnitude of current flowing through it
(C) Both (A) and (B)
(D) None of the above

Answer: Option A

Q 87. Conductance is reciprocal of

(A) Resistance
(B) Inductance
(C) Reluctance
(D) Capacitance

Answer: Option A

Q 88. Which of the following material has nearly zero temperature coefficient of resistance?

(A) Manganin
(B) Porcelain
(C) Carbon
(D) Copper

Answer: Option A

Q 89. 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

Answer: Option B

Q 90. The rating of a fuse wire is always expressed in

(A) Ampere-hours
(B) Ampere-volts
(C) kWh
(D) Amperes

Answer: Option D

Q 91. A 3 Q resistor having 2 A current will dissipate the power of

(A) 2 watts
(B) 4 watts
(C) 6 watts
(D) 8 watts

Answer: Option C

Q 92. If a wire conductor of 0.2 ohm resistance is doubled in length, its resistance becomes

(A) 0.4 ohm
(B) 0.6 ohm
(C) 0.8 ohm
(D) 1.0 ohm

Answer: Option A

Q 93. A closed switch has a resistance of

(A) Zero
(B) About 50 ohms
(C) About 500 ohms
(D) Infinity

Answer: Option A

Q 94. 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

Answer: Option C

Q 95. With rise in temperature the resistance of pure metals

(A) Increases
(B) Decreases
(C) First increases and then decreases
(D) Remains constant

Answer: Option A

Q 96. Resistance of a tungsten lamp as applied voltage increases

(A) Decreases
(B) Increases
(C) Remains same
(D) None of the above

Answer: Option B

Q 97. When one leg of parallel circuit is opened out the total current will

(A) Reduce
(B) Increase
(C) Decrease
(D) Become zero

Answer: Option C

Q 98. Resistance of carbon filament lamp as the applied voltage increases.

(A) Increases
(B) Decreases
(C) Remains same
(D) None of the above

Answer: Option B

Q 99. Two bulbs of 500 W and 200 W rated at 250 V will have resistance ratio as

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

Answer: Option C

Q 100. For testing appliances, the wattage of test lamp should be

(A) Very low
(B) Low
(C) High
(D) Any value

Answer: Option C