1. A battery of e.m.f. 15V supplies a current of 2A for 5 min. How much energy is supplied in this time? 2. Calculate the power dissipated by the element of an electric fire of resistance 30 0 when a current of 10A flows in it. If the fire is on for 30 hours in a week determine the energy used. 3. Determine the resistance of an electric fire which takes a current of 12A from a 240V supply. Find also the power rating ofthe fire and the energy used in 20 h. 4. Resistances of 10 0, 20 Q and 30 Q are connected (a) in series and (b) in parallel to a 240V supply. Calculate the supply current in each case