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Electrical Engineering Objective Questions { Basic Concept of Electricity }

113. The coercive force in a ferrowmagnetic material is related to the
A. area enclosed by the B-H loop.
B. intercept on the negative 1-1 axis of the B-H loop
C. intercept on the positive B axis of the B-H loop
D. maximum value of B on the B-H loop

114. Hysteresis loss is caused by
A. structural non-homogeneity
B. work required for magnetizing the material
C. potential work function
D. none of the above

115. Hysteresis loss is proportional to
A. f
B. f15
C. f2
D. f3k

116. The energy stored in the magnetic field of a solenoid 30 cm. long and 3 cm diameter would with 1,000 turns of wire carrying current of 10 A is
A.0.015 J

117. A coil with a certain number of turns has a specified time constant. If the number of turns is doubled, its time constance would
A. remain unaffected.
B. become double
C. become four fold.
D. get halved

118. At a certain current, the energy stored a an iron-corred coil is 1,000 J and its copper loss is 2,000W. The time constant (in seconds) of the coil is

119. Two coils having equal resistance but different inductances are connected in series. The time constant of the series combination is the
A. sum of time constant of the individual coils.
B. geometric mean of time constants of the individual coils
C.(d) product of the time constant of the individual coils.

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