JAMB - Physics (2005 - No. 15)
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.
200
100
250
150
Explication
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
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