A certain ac signal at 1000 Hz is applied across an inductor and a 100-Ω resistor. If the power factor of the circuit is 0.400, what is the impedance of this circuit?
A) 150 Ω
B) 200 Ω
C) 250 Ω
D) 100 Ω
E) 300 Ω

Question

Quizplus · Accepted Answer

The power factor of the circuit is given by the ratio of the resistance to the total impedance of the circuit:

cos θ = R/Z

where θ is the phase angle between the current and the voltage.

Given that the power factor is 0.4, we can write:

0.4 = 100/ Z 
Z = 100/0.4 = 250 Ω

Therefore, the impedance of the circuit is 250 Ω.

A Certain Ac Signal at 1000 Hz Is Applied Across