(a)i) of resonance frequency as applied to RLC series circuit
- It is the frequency of oscillation of an RLC series circuit when the capacitive reactance is equal to the inductive reactance. The impedance is equal to the resistance /the impedance is minimum.
(ii) A sketched graph

(iii) $\alpha$ Relationship between current and voltage when f = f${}_o$;
Current is in phase with the supply voltage ($\beta$)
- Relationship when current and voltage when f = f${}_o$;
Current lags the Supply voltage ($\gamma$)
- Relationship between current and voltage when f > f${}_o$;
Current leads the supply voltage.

(b) (i) Definition of mutual inductance:
The ratio of the induced emf in one coil/circuit to the time rate of change of current in the other coil. OR The production of e.m.f in a circuit as a result of the change in the magnetic flux/magnetic circuit in an adjacent circuit linked to it
.
(ii) Calculation of angular speed of the coil of an electric generator: E = $\omega$BAN
480 = $\omega$ x 0.25 x $\pi$ x ($\frac{8.0\times {10}^{-2}}{2}$) x 500 = $\omega$ = 763.8 rad/s

(c)(i) of eddy current:
The current is induced and flows within a metal block when there is a change in magnetic flux linking the block.
OR
Loops of electric current induced within a conductor by the changing magnetic flux/field in the conductor.

OR
The localised electric current/loops of electric current
(ii) Practical Uses of eddy current:
- induction furnaces
- induction coils
- speedometers
- induction meters