Question

What is the peak power consumption of a 120-V AC microwave oven that draws 10.0 A?

Final Answer

$2.40 \textrm{ kW}$

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Video Transcript

This is College Physics Answers with Shaun Dychko.
The peak power consumption of the microwave will be the peak voltage multiplied by the peak current that occurs when the peak voltage happens. So we need to figure out what these

*V naught*and*I naught*are based on our formula for*V RMS*and*I RMS*. So the RMS voltage is the peak voltage divided by root two and so we solve for peak voltage by multiplying both sides by root two. We get*V naught*peak voltage equals root two times*V RMS*. You could take the same approach to find*I naught*which is going to be root two times*I RMS*. So we substitute each of these in place of*V naught*and*I naught*here, and this works out to two, because that's what root two times root two is, multiplied by*V RMS*times*I RMS*. When you're given a value for the voltage of the household plug, you have to assume that that's an RMS voltage. It's always RMS numbers that are quoted unless it specifically says that it's a peak voltage that's quoted. So when the question says 120 volt AC microwave oven that draws 10 amps both those figures given, 120 volts and 10 amps given, those are RMS numbers. So we multiply them together and times by two and we get 2.40 kilowatts.