ELEC 06001

In a purely inductive AC circuit, what is the phase relationship between the current and the voltage?

• Current leads voltage by 90°

• Current lags voltage by 90°

• Current and voltage are in phase

• Current and voltage are 180° out of phase

What is the primary purpose of using thin laminated sheets in the core of a transformer or relay?

• To increase the magnetic flux

• To reduce hysteresis losses

• To reduce eddy current losses

• To increase the inductance

In an AC circuit, what happens to the inductive reactance of a coil if the frequency of the AC supply is doubled?

• It doubles

• It halves

• It remains the same

• It quadruples

What is the term used to describe the opposition to a change in current in an inductive circuit?

• Capacitive reactance

• Impedance

• Inductive reactance

• Resistance

In a purely capacitive AC circuit, what is the phase relationship between the current and the voltage?

• Current leads voltage by 90°

• Current lags voltage by 90°

• Current and voltage are in phase

• Current and voltage are 180° out of phase

What is the formula to calculate the capacitive reactance (Xc) of a capacitor in an AC circuit?

• Xc = 1 / (2πfC)

• Xc = 2πfC

• Xc = 1 / (2πfL)

• Xc = 2πfL

What is the power factor of a circuit if the real power (P) is 100 W and the apparent power (S) is 125 VA?

• 0.6

• 0.75

• 0.8

• 1.0

Which of the following best describes Lenz's Law?

• The induced current opposes the change in magnetic flux

• The induced current enhances the change in magnetic flux

• The induced current is independent of the magnetic flux

• The induced current is proportional to the resistance

What is the effect of increasing the number of turns in a coil on its inductance?

• Inductance decreases

• Inductance increases

• Inductance remains the same

• Inductance becomes zero

In an AC generator, at which points during the rotation of the conductor is the maximum EMF produced?

• 0° and 180°

• 90° and 270°

• 45° and 225°

• 60° and 240°