(i)

Earthing is the transfer of electrical charges from the atmosphere directly to the earth through a wire buried in the ground. This is done to conduct excess charges/current on an appliance safely to earth or to prevent the user of the appliance from getting electric shock or to protect the circuit breaker/fuse/electrical appliances

(ii)

Sources of electric power generation

1. Battery/Cell
2. Solar
3. Wind
4. Biogas
5. Nuclear
6. Hydro/water
7. Diesel

(i)

Ohm's law states that the current flowing through a metallic conductor at a constant temperature is proportional to the potential difference across it.

OR

V = IR,
where V = voltage or P.d
      I = current,
      R = resistance.

(ii)

V = IR

Current(I) = 10 A
Resistance(R) = 12.5 Ω

Potential difference/voltage = 10 x 12.5 V = 125 V