The expected answers were:

(i) Cause of Hysteresis loss: This is the energy expended in causing the magnetisation in a core in the form of heat.

(ii)Cause of Copper loss: It is the heating of the conductors due to the fact that they posses resistance.
 (b)(i)  Application of single-phase transformer 
 Constant voltage application; impedance matching; protection; inverters; communication system, domestic appliances.
(ii)    Application of three-phase transformer
Power distribution system, 3-phase inverter communication system

Power  transmission

Power distribution

(c)Ep  =  NP
     Es      Ns

240 = 1800
12         Ns

     Ns  = 1800 x 12  =90 turns
                   240
This question was on Alternating Current Machine. It was quite popular. The performance was satisfactory.

A handful of the candidates attempted this question. However, not many of the candidates that attempted this question could explain the cause of hysteresis and copper losses nor give any application. Almost all of them who attempted this got part(c), but report show that causes of losses in transformer  was not understood by them probably they were not taught.