Question

A transformer has 400 turns in the primary winding and 10 turns in the secondary winding. The primary e.m.f. is 250 V and the primary current is 2.0 A. calculate:
(a) The secondary voltage,
(b) The secondary current, assuming 100% efficiency.

Answer 1

Since, the number of turns in the primary is more than the no. of turns in the secondary it is a step-down transformer.

Given, N_P= 400, N_s = 10, E_P=250 V, I_P= 2A

(a) Let Es be the secondary voltage.

We know that for transformer turn ratio `"N"_"s"/"N"_"p" = "I"_"p"/"I"_"s" = "E"_"s"/"E"_"P"`

E_s = `"N"_"s"/"N"_"P" xx "E"_"P" = 10/400 xx 250 = 6.25 "V"`

(b) Let Is be the current though secondary

We know that for transformer turn ratio `"N"_"s"/"N"_"P" = "I"_"P"/"I"_"s"`

I_s  = `400/10 xx 2= 80 "A"`