Compute all parts of given question;
Question: A "540 W" electric heater is designed to operate from 120V lines.
Part A: What is its resistance?
Part B: What current does it draw?
Part C: At 7.0 cents per kWh, how much does it cost to operate this heater for an hour?
Part D: If the line voltage drops to 110V, what power does the heater take, in watts? (Assume that the resistance is constant, although it actually will change because of the change in temperature).
I am having a hard time understanding these questions. So if you answer please explain how you found the answers.