Household electricity is supplied in the form of alternating current that varies from 155V to – 155V with a frequency of 60 cycles per second (Hz). The voltage is thus given by the equation E(t) = 155 sin (120πt) where the time in seconds is.
Voltmeters read the RMS (root-mean-square) voltage, which is the square root of the average value of [E (t)] 2 over one cycle.
(a) Calculate the RMS voltage of household current.
(b) Many electric stoves require an RMS voltage of 220 V.
Find the corresponding amplitude A needed for the voltage E (t) = A sin (120πt).