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A transformer is rated 240v. If the primary coil is 4000 ...

A transformer is rated 240v. If the primary coil is 4000 turns and the secondary voltage 12v, determine the number of turns in the secondary coil.

A.

200

B.

100

C.

250

D.

150

Correct answer is A

in a transformer, E S/E P = N s/N p
where E s=e.m.f(voltage)of the secondary
E p=e.m.f(voltage)of the primary
N s=no.of turns in the secondary
N p= no. of turns in the primary.
since E s= V s; and E p= V p.
V s/ V p= N s/N p
∴12/240= Ns/4000
Ns =(12x4000)/240
=200