AC Power

What is the unit of true power (P)?

• Volt-Amperes (VA)

• Watts (W)

• Volt-Amperes Reactive (VAR)

• Ohms (Ω)

Which of the following represents apparent power (S)?

• The product of voltage and current

• The sum of true power and reactive power

• The product of true power and reactive power

• The ratio of true power to reactive power

What is the mathematical relationship between apparent power (S), true power (P), and reactive power (Q)?

• S=P+Q

• S2=P2+Q2

• P=S×Q

• S=P−Q

What is the unit of reactive power (Q)?

• Volt-Amperes Reactive (VAR)

• Watts (W)

• Volt-Amperes (VA)

• Joules (J)

What is the power factor (PF)?

• The ratio of reactive power to apparent power

• The ratio of true power to apparent power

• The ratio of apparent power to reactive power

• The product of true power and apparent power

What does a power factor of 1 indicate?

• All the power is reactive

• All the power is true power

• Apparent power is equal to reactive power

• There is no reactive power

What happens when the power factor is less than 1?

• The system uses more current for the same amount of power

• The system uses less current for the same amount of power

• True power exceeds apparent power

• Apparent power is minimized

What is the effect of inductive loads on power factor?

• They improve the power factor

• They decrease the power factor

• They have no effect on power factor

• They make power factor equal to 1

Which of the following devices is used to improve power factor in an AC circuit?

• Inductor

• Capacitor

• Transformer

• Resistor

f a circuit has a power factor of 0.8 lagging, what does the "lagging" indicate?

• The current leads the voltage

• The voltage leads the current

• The current lags the voltage

• Both voltage and current are in phase