Let Vp, Ip and Np be the voltage, the current and the number of turns of the primary of an electric transformer and Vs, Is and Ns be the voltage, the current and the number of turns of its secondary. If this transformer is not 100% efficient, which of the following must be true?
A) Vp = Vs
B) Vs Is > Vp Ip
C) Vs Is = Vp Ip
D) Ip = Is
E) Vs Is < Vp Ip