If a step-up transformer has a primary coil with 40 turns, how many turns would be required in the secondary coil in order to increase the voltage from 80 volts to 160 volts?

In a step-up transformer, the relationship between voltages on the primary and secondary coil and the number of turns in the two coils is

where V means voltage, N is the number of turns, and p and s refer to the primary and secondary coil, respecitvely.

In our example, we have Vp=80 V and Vs=160 V, and the primary coils have Np=40 turns, so we can find the number of turns in the secondary coil, Ns:
turns