85. Time constant of a circuit is the time in second taken after the application of voltage to each

A. 25% of maximum value

B. 50(Yoof maximum value

C. 63% of maximum value

D. 90% of the maximum value

86. Time constant of an inductive circuit

A. increases with increase of inductance and decrease of resistance

B. increases with the increase of inductance and the increase of resistance

C. increases with the decrease of inductance and decrease of resistance

D. increases with decrease of inductance and increase of resistance

87. Time constant of a capacitive circuit

A. increases with the decrease of capacitance and decrease of resistance

B. increases with thedecrease of capacitance and increase of resistance

C. increases with the increase of capacitance and decrease of resistance

D. increase with increase of capacitance and increase of resistance

88. Magnitude of current at resonance in R-L-C circuit

A. depends upon the magnitude of R

B. depends upon the magnitude of L

C. depends upon the magnitude of C

D. depends upon the magnitude of R, L and C

89. Power factor of magnetising component of current of a transformer is

A. 0.8 lag

B. 0.8 lead

C. zero

D. unity

90. In a R-L-C circuit

A. power is consumed in resistance and is equal to I2R

B. exchange of power takes place between inductor and supply line

C. exchange of power takes place between capacitor and supply line

D. All the above

91. Physical quantities of resistance, inductance and capacitance are represented by R, L and C respectively.The combinations which have dimensions of frequency are

A. C/L

B.R/L

C. 1/RC

D. 1/ 1/.7

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