E04 AC

In a parallel ac circuit with XL and XC,

• IL and Ic are 90° out of phase.

• IL and IC are in phase.

• IL and IC are 180° out of phase.

• XL and XC are 90° out of phase.

What is the term for the out-of-phase power associated with inductors and capacitors?

• Effective power.

• True power.

• Peak envelope power.

• Reactive power.

In an AC circuit, if the voltage and current are in phase, the circuit is

• resistive

• capacitive

• reactive

• inductive

For a capacitor in a sine-wave ac circuit,

• Vc lags ic by 90°

• ic leads Vc by 90°

• ic and Vc have the same frequency.

• All of the above.

Calculate the r.m.s. value of a sinusoidal current of maximum value 20A.

• 7.07 A

• 14.14 A

• 28.28 A

• 26.25 A

An alternating voltage is given by v=75 sin (200πt −0.25) volts. Find the phase angle (in degrees and minutes)

• 14.32 (lagging)

• 14.32 (leading)

• 31.83 (lagging)

• 31.83 (leading)

In a parallel RL circuit,

• IL lags IR by 90°.

• IL leads IR by 90°.

• IL and IR are in phase.

• IR lags IL by 90°.

Calculate the current taken by a 10 μF capacitor when connected to a 200 V, 100 Hz supply.

• 0.1257 A

• 125.7 A

• 12.57 A

• 1.257 A

What is the power factor (PF) of a purely resistive ac circuit?

• 0.

• 1.

• 0.707.

• Without values, it cannot be determined.

A resistive and a capacitive load of equal magnitude is connected in series, determine the phase difference between the voltage and the current.

• current leads the voltage by 45°

• current lags the voltage by 45°

• current leads the voltage by 90°

• current lags the voltage by 90°