Current Electricity

81. Two resistors are said to be connected in series when

  1. same current passes in turn through both
  2. both carry the same value of current
  3. total current equals the sum of branch currents
  4. sum of IR drops equals the applied e.m.f.

Correct answer: (A)
same current passes in turn through both

82. Varistors are

  1. insulators
  2. non-linear resistors
  3. carbon resistors
  4. resistors with zero temperature coefficient

Correct answer: (B)
non-linear resistors

83. Voltage dependent resistors are used

  1. for inductive circuits
  2. to supress surges
  3. as heating elements
  4. as current stabilizers

Correct answer: (B)
to supress surges

84. Voltage dependent resistors are usually made from

  1. charcoal
  2. silicon carbide
  3. nichrome
  4. graphite

Correct answer: (C)
nichrome

85. What will be energy used by the battery if the battery has to drive 6.28 x 1018 electrons with potential difference of 20 V across the terminal?

  1. 5 joules
  2. 10 joules
  3. 15 joules
  4. 20 joules

Correct answer: (A)
5 joules

86. 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

  1. 1 n-mho
  2. 106 mho
  3. 1 milli-mho
  4. none of the above

Correct answer: (A)
1 n-mho

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

  1. current through supply line flows at slower speed
  2. supply wiring is covered with insulation layer
  3. resistance of heater coil is more than the supply wires
  4. supply wires are made of superior material

Correct answer: (C)
resistance of heater coil is more than the supply wires

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

  1. A.C.
  2. D.C.
  3. any of above two
  4. none of the above

Correct answer: (B)
D.C.

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

  1. collisions between conduction electrons and atoms
  2. the release of conduction electrons from parent atoms
  3. mutual collisions between metal atoms
  4. mutual collisions between conducting electrons

Correct answer: (A)
collisions between conduction electrons and atoms

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

  1. reduce
  2. increase
  3. decrease
  4. become zero

Correct answer: (C)
decrease

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