The rechargeable batteries for a laptop computer need a much smaller voltage than what a wall socket provides. Therefore, a transformer is plugged into the wall socket and produces the necessary voltage for charging the batteries. The batteries are rated at 9.0 V, and a current of 243 mA is used to charge them. The wall socket provides a voltage of 120 V. Determine the turns ratio of the transformer. Ns/Np= 075 What is the current coming from the wall socket? Ip = X A Find the average power delivered by the wall socket and the average power sent to the batteries. Pp= w Ps = W
Explanation / Answer
(b) The current from wall socket] Ns / Np = Ip /Is then Ip = (Ns/Np) Is = (0.075) (243mA) = 18.225 mA (c) The power delivered P = VpIp = (120) (18.225 *10-3) = 2.187 W and Ps = Vs Is = (9) (243*10-3) = 2.187 W