The root mean square value of an alternating current is
- A. equal to its peak value
- B. the peak value divided by the square root of 2
- C. the peak value multiplied by 2
- D. always zero
Explanation
The rms value is about 0.707 of the peak and is defined as the steady direct current that would dissipate the same power in a given resistor. Mains electricity quoted as 220 V is an rms figure, so the peak is around 311 V, which is why insulation must be rated well above the nominal value. The simple average over a full cycle is zero, which is why the rms measure is needed at all.
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