Alternating current

The rms value of an AC with peak value 10 A is:

• 1 14.1 A
• 2 7.07 A
• 3 10 A
• 4 5 A

In a purely resistive AC circuit, the current and voltage are:

• 1 180 degrees apart
• 2 90 degrees apart
• 3 Unrelated
• 4 In phase

Capacitive reactance is given by:

• 1 2 pi f L
• 2 2 pi f C
• 3 1 / (2 pi f L)
• 4 1 / (2 pi f C)

Inductive reactance:

• 1 Increases with frequency
• 2 Decreases with frequency
• 3 Is zero always
• 4 Does not change

At resonance in a series LCR circuit, the impedance is:

• 1 Infinite
• 2 Minimum and equal to R
• 3 Maximum
• 4 Zero

The frequency of mains AC in Pakistan is:

• 1 50 Hz
• 2 25 Hz
• 3 100 Hz
• 4 60 Hz

A choke coil reduces AC with little loss of power because it has high:

• 1 Capacitance
• 2 Mass
• 3 Resistance
• 4 Inductive reactance

The power factor of a purely resistive circuit is:

• 1 0.5
• 2 1
• 3 0
• 4 Infinite