Complex AC MCQs

Question 1

Pure inductive circuit takes power from the A.C. line when

Accepted Answer

applied voltage decreases but current increases

Answer

applied voltage increases but current decreases

Answer

both applied voltage and current in crease

Answer

both applied voltage and current decrease

Question 2

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

Accepted Answer

63% of maximum value

Answer

25% of maximum value

Answer

50(Yoof maximum value

Answer

90% of the maximum value

Question 3

Time constant of a capacitive circuit

Accepted Answer

increase with increase of capacitance and increase of resistance

Answer

increases with the decrease of capacitance and decrease of resistance

Answer

increases with thedecrease of capacitance and increase of resistance

Answer

increases with the increase of capacitance and decrease of resistance

Question 4

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

Accepted Answer

depends upon the magnitude of R

Answer

depends upon the magnitude of L

Answer

depends upon the magnitude of C

Answer

depends upon the magnitude of R, L and C

Question 5

Power factor of magnetising component of current of a transformer is

Accepted Answer

zero

Answer

0.8 lag

Answer

0.8 lead

Answer

unity

Question 6

In a R-L-C circuit

Accepted Answer

All the above

Answer

power is consumed in resistance and is equal to I2R

Answer

exchange of power takes place between inductor and supply line

Answer

exchange of power takes place between capacitor and supply line

Question 7

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

Accepted Answer

1/ 1/.7

Answer

C/L

Answer

R/L

Answer

1/RC

Question 8

In a R-L-C series circuit if voltage V across the cirucit is reduced to half the current I will change to

Accepted Answer

?

Answer

21

Answer

3/4 I

Answer

5/8 I

Question 9

The time constant of a series R-C circuit is given by

Accepted Answer

RC

Answer

R/C

Answer

RC2

Answer

R2C