Question

A transformer with a primary of 400 turns is connected across a 120v a-c line. the secondary circuit has a potential difference of 300v. the secondary 0.06a and the primary current is 1.85a. how many turns are in the secondary winding? b). what is the transformer efficiency?

Answer 1

Gives

$N_1=400$

$N_2=?$

$V_1=120V$

$V_2=300$

$I_1=0.06A$

$I_2=1.85A$

$P_1=I_1V_1$

$P_2=V_2I_2$

We know that

Potential proportional to number of turns

$\frac{V_2}{V_1}=\frac{N_2}{N_1}$

$N_2=\frac{V_2}{V_1}\times N_1$

Put value

$N_2=\frac{300}{120}\times400=1000$

$P_1=120\times0.06=7.2W$

$P_2={300}\times1.85=555W$

efficiency=$\frac{P_2}{P_1}=\frac{555}{7.2}=77.08$