Electricity 2 — AC Circuits

Peak vs RMS

"120 V" from the wall is not the peak — it is the RMS value: the steady DC voltage that would deliver the same power. For a sine wave, RMS = peak/√2.

V_{pk} := 170 V

= 170 V what the wall actually peaks at

V_{rms} = \frac{V_{pk}}{\sqrt{2}}

= 120.21 V the 120 V on the label