The expected answers were:
(a) Faraday’s Law of electromagnetic induction states that whenever there is a change in the magnetic flux linked with a conductor in a closed circuit, e.m.f. is induced in the conductor which causes a current to flow in it.
OR
(b) The strength of the induced e.m.f. is directly proportional to the rate of change of magnetic flux.
(i) Capacitance of the capacitor
C = ∑o ∑r A/d (n-1)
C = 8.85 x 10-12 x (6 * 6 * 0.05) / 0.0005
C = 31.86nF
(ii) Charge in the capacitor
Q = CV
= 31.86 x 10-9 x 400 ; Q = 12.74μC
This question was on electromagnetic field. Many candidates attempted the part (a) of the question but avoided part (b). However, the expression for calculating C for multiple plate capacitor was wrongly quoted by many candidates and consequently missed it.