Basics of ac circuits: A 500-W device is connected to a 230-V ac power source. What rms current flows through this device?

Question

Quizplus · Accepted Answer

The power equation for an ac circuit is P = Vrms * Irms * cos⁡(θ), where P is power, V is voltage, I is current, and θ is the phase angle between voltage and current. Since the device is connected to a 230-V ac power source and has a power of 500 W, we can rearrange this equation to solve for Irms:

Irms = P / (Vrms * cos⁡(θ))

We assume that θ = 0, since the problem statement does not provide any information to suggest otherwise. Therefore, we have:

Irms = 500 W / (230 V) = 2.17 A

Rounding to the nearest tenth, we get the answer of 2.2 A (choice B).

Basics of Ac Circuits: a 500-W Device Is Connected to a 230-V