Suppose that you want to build a transformer that will convert 80 V power coming in the primary coil to 120 V power going out of the secondary coil. If you want to have a total of 20 turns, how many turns should you have in the primary coil?
We can use the formula for transformer voltage ratio:
Vp/Vs = Np/Ns
Where Vp is the voltage in the primary coil, Vs is the voltage in the secondary coil, Np is the number of turns in the primary coil, and Ns is the number of turns in the secondary coil.
Plugging in the values we have:
80/120 = Np/20
Solving for Np:
Np = (80/120) x 20
Np = 13.33
We cannot have a fractional number of turns, so we round up to the nearest whole number:
Np = 14
Therefore, the primary coil should have 14 turns in order to convert 80 V power to 120 V power.