The primary of a stepdown transformer has 200 turns and is c

The primary of a step-down transformer has 200 turns and is connected to a 120 V rms line. The secondary is to supply 40 A at 15 V. (a) Find the current in the primary. A (b) Find the number of turns in the secondary, assuming 100% efficiency.

Solution

Here ,

Np = 200

Vp = 120 V

Vs = 15 V

Is = 40 A

a) let the current in the primary is Ip

as Vp * Ip = Is * Vs

120 * Ip = 15 * 40

Ip = 5 A

the current in the primary is 5 A

b)

for an ideal transformer

Vp/Vs = Np/Ns

120/15 = 200/Ns

Ns = 50

the number of turns in secondary is 50