Transformer construction and working

TRANSFORMER

Definition:

Electrical device used to increase the
value alternating current or voltage

Working
Principle:

it works on the principle of mutual
induction.

Construction:

It consists of :

•Soft
iron core

•Primary
coil

•Secondary
coil

Working:


When the primary coil is connected to a source of AC voltage, the changing
current creates a changing magnetic field, which is carried through the core to
the secondary coil.

 In
the  secondary coil, the changing field
induces an alternating e.m.f.

The e.m.f.
induced in the secondary coil, called the secondary voltage VS, is
proportional to the

primary voltage VP. The
secondary voltage also depends on the ratio of the number of turns on the
secondary coil to the number of turns on the

primary coil

V_S∝V_p

V_S=N_S/N_P  V_p

V_s/V_p =N_S/N_P

Step
up transformer:

Transformer used to increase the value
of  AC voltage

Step
Down Transformer:

Transformer used to decrease the value
of  AC voltage

Ideal
Transformer

In an ideal transformer, the electric
power delivered to thesecondary
circuit is equal to the power supplied to the primary circuit. An ideal
transformer dissipates no power itself, and for such a transformer, we can
write