64. Power factor of the following circuit will be zero
A. resistance
B. inductance
C. capacitance
D. both (b) and (c)
65. Power factor of the following circuit will be unity
A. inductance
B. capacitance
C. resistance
D. both (a) and (b)
66. Power factor of the systemis kept high
A. to reduce line losses
B. to maximise the utilization of the capacities of generators, lines and transformers
C. to reduce voltage regulation of the line
D. due to all above reasons
67. The time constant of the capacitance circuit is defined as the time during which voltage
A. falls to 36.8% of its final steady value
B. rises to 38.6% of its final steady value
C. rise to 63.2% of its final steady value
D. none of the above
68. In the R-L-C containing R = 4.5 SI, L = 0.06 H, C = 0.6 tff the power factor will be
A. zero
B. lagging
C. leading
D. unity
69. In a loss-free R-L-C circuit the transient current is
A. oscillating
B. square wave
C. sinusoidal
D. non-oscillating
70. The r.m.s. value of alternating current is given by steady (D.C.) current which when flowing through a given circuit for a given time produces
A. the more heat than produced by A.C. when flowing through the same circuit
B. the same heat as produced by A.C. when flowwing through thesame circuit
C. the less heat than produced by A.C. flowing through the same circuit
D. none of the above
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