(a) A magnetic field is a region or space where a magnetic force is experienced.
(b)

Connect a straight wire to the circuit as shown above, sprinkle iron fillings on the cardboard paper round the straight wire; and tap gently. Then close the key and gently tap again, the iron fillings form a concentric circles round the wire. This shows that there is magnetic field round a current carrying conductor.

(c)(i)

\(x_c = \frac{1}{2 \pi fc} = \frac{1}{2 \pi \times 50(40 \times 10^{-6})}\)
= 79.567\(\Omega\)
z = \(\sqrt{R^2 + X^2_c} = \sqrt{40^2 + 79,580^2}\)
(ii) I = \(\frac{v}{2} = \frac{100}{89.1} = 1.12A\)
(iii) V = IX\(_c\) = 1.12 x 79.567
= 89.1V