MCQ of Transformer page-8

71. When the secondary of a transformer is loaded, the current in the primary side will

a) Not be effected
b) Increase
c) Decrease
d) Be the sum of no-load current and excess current drawn due to the secondary current

Ans: (d)

72. Electric power is transferred from one coil to the other coil in a transformer

a) Magnetically
b) Physically
c) Electromagnetically
d) Electrically

Ans: (a)

73. A transformer operates

a) Always at unity power factor
b) Has its own constant power factor
c) At a power factor always below 0.8
d) At power factor depending on the power factor of the load

Ans: (d)

74. In an ideal transformer on no-load, the primary applied voltage is balanced by

a) Secondary induced emf
b) Primary induced emf
c) Drop across resistance and reac-tance
d) The secondary voltage

Ans: (a)

75. In a transformer, the no load current in terms of full load current is of the order of

a) 1 to 3%
b) 3 to 10%
c) 10 to 20%
d) 20 to 30%
Ans: (a)

76. Cross-over windings are used for

a) High voltage winding of small rating transformer
b) Low voltage winding of small rating transformer
c) High voltage winding rating of large transformer
d) Low voltage winding of large rating transformer

Ans: (a)

77. Advantage of putting tappings at the phase ends of a transformer is

a) Fine variation of voltage
b) Ease of operation
c) Reduction in number of bearings
d) Better regulation

Ans: (c)

78. The yoke sections of transformers using hot-rolled laminations is made about 15% larger than that of the core in order to

a) Reduce copper loss
b) Increase the size of transformer
c) Provide better cooling
d) Reduce iron loss in yoke and magnetizing current

Ans: (d)

79. The primary and secondary windings of an ordinary transformer always have

a) Copper wire of same diameter
b) Common magnetic circuit
c) Different number of turns
d) Separate magnetic circuits

Ans: (b)

80. The leakage flux of a transformer is defined as

a) The flux which is linked with both the primary and the secondary windings
b) The flux which is linked either only with the primary or only with the secondary
c) The flux whose path is exclusively through the air
d) None of these

Ans: (b)

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241. Which of the following statement is true? a) The saturation voltage V_CF of silicon transistor is more than germanium transistor.
b) The saturation voltage V_CE for germanium transistor is more than silicon transistor.
c) The saturation voltage V_CE for silicon transistor is same as that for germanium.
d) The saturation voltage V_CE for silicon transistor is lower than germanium transistor.

Multiple Choice Question (MCQ) of Electronics page-16:
226. Which of the following statement is correct? a) Inner electrons are always present in the semiconductor.
b) Bound electrons are always present in the semiconductor.
c) Free electrons are always present in the semiconductor.
d) Inner and bound electrons are always present in the semiconductor.

Multiple Choice Question (MCQ) of Electronics page-15:
211. The materials whose electrical conductivity is usually less than 1 × 10⁶ mho/m are a) Semiconductors
b) Conductors
c) Insulators
d) Alloys

Multiple Choice Question (MCQ) of Electronics page-14:
196. In which of the following device the base resistors are not added in the package but added externally? a) UJT
b) CUJT
c) PUT
d) None of the above

Multiple Choice Question (MCQ) of Electronics page-13:
181. The conduction in JEFT is always by the a) Majority carriers
b) Minority carriers
c) Holes
d) Electrons
e) Holes and electrons simultaneously

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MCQ of Transformer page-8

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