(a) (i) Neutral point is a point at which the resultant magnetic flux density is zero.
(ii)

(b)(i) (ii) An ammeter is accurate if the current it mea-sures is close to the true value of the current flowing through the instrument.

(c)

The material is surrounded by a thick wall of ferro-magnetic material which does not allow magnetism to pass through them. This shields or protects the material from the earth's magnetic field.
(ii) F = qvBsin\(\theta\) = 1.6 x 10\(^{-19}\) x 2.5 x 10\(^{7}\) x 2 x 0.5 = 4 x 10\(^{2}\) N
(d) Electromagnetic induction laws are
- Whenever there is a change in the magnetic flux linked with a circuit, an e.m.f is induced, the magnitude of which is proportional to the rate of change of the flux linked with the circuit.
- The direction of the induced current is always such as to oppose the change producing it.