The expected answers were:
(a) The function of the commutator in a d.c. machine is to provide
     (i)        excitation to the field windings
     (ii)       provide an output from the machine through brushes
     (iii)      rectify the a.c. in or out of the armature
(b) (i) If= V/Rf = 160/80 = 2 A
(ii) la = I - If = 30 - 2 = 28 A
(iii)E = V + laRa
= 160 + (28 x 0.6) = 176.8 V
The question was on Electrical Machines (D.C.). The question was popular. The performance was relatively good.

Many candidates could not state the function of commutator in a d.c. machine. However, as many of them that attempted the part (b), the calculation aspect, got it correctly.