(a) Two bulbs are marked 100W, 220V and 60W, 110V. Calculate the ratio of their resistances.
(b) (i) What is the colour code for insulation of earth wire?
(ii) Write an expression for calculating electric power in terms of current and resistance.
(c) (i) Name two safety devices which are connected to the live wire of a household electrical circuit.
(ii) Give one important function of each of these devices.
(d) (i) An electric bulb is marked 100W, 250V. What information does this convey?
(ii) How much current will the bulb draw if connected to 250V supply?
