A current of 0.2 A flows through a wire whose ends are at a potential difference of 20 V. Calculate —

(i) the resistance of the wire, and

(ii) the heat energy produced in 1 minute.

What is the resistance, under normal working conditions, of an electric lamp rated at '240 V, 60 W'? If two such lamps are connected in series across a 240 V mains supply, explain why each one appears less bright.

An electric bulb is rated '250 W, 230 V'. Calculate

(i) the energy consumed in one hour, and

(ii) the time in which the bulb will consume 1.0 kWh energy when connected to 230 V mains?

Three heaters each rated 250 W, 100 V are connected in parallel to a 100 V supply.

Calculate —

(i) The total current taken from the supply,

(ii) the resistance of each heater, and

(iii) the energy supplied in kWh to the three heaters in 5 hours.