A typical wall outlet voltage is 120 volts in the United Sta

A typical wall outlet voltage is 120 volts in the United States. Personal MP3 players require much smaller voltages, typically 709.5 mV. If the number of turns in the primary coil is 1353, calculate the number of turns on the secondary coil of the adapter transformer. What is the relationship between the voltages across the primary and secondary coils, respectively, of a transformer, and the number of turns in each coil?

Solution

In transformers:

Np/Ns = Vp/Vs

Ns = Np*Vs/Vp

Ns = 1353*709.5*10^-3/120 = 7.99 turns

Ns = 8 turns