Question

(a) Draw a schematic arrangement for winding of primary and secondary coil in a transformer when the two coils are wound on top of each other. 

(b) State the underlying principle of a transformer and obtain the expression for the ratio of secondary to primary voltage in terms of the 

(i) number of secondary and primary windings and 

(ii) primary and secondary currents. 

(c) Write the main assumption involved in deriving the above relations. 

(d) Write any two reasons due to which energy losses may occur in actual transformers.

Answer 1

(b) Principle of a transformer : When an alternating current flows through the primary coil, an emf is induced in the neighbouring (secondary) coil.

(c) Main assumptions

(i) The primary resistance and current are small.

(ii) The flux linked with the primary and secondary coils is same / there is no leakage of flux from the core.

(iii) Secondary current is small.

(d) Reason due to which energy loses may occur : 

Flux leakage/Resistance of the coils/ Eddy currents/ Hysteresis