set of Christmas tree lights is made from twenty identical lamps connected in series.(a) Each lamp is designed to take a current of 0.25 A. The set plugs directly into the 230 V mains electricity supply.(i) Write down the equation that links current, potential difference and resistance.________________________________________________________________________________________________________________________________________________________(1)(ii) Calculate the resistance of one of the lamps. Show clearly how you work out your final answer and give the unit.________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________Resistance = ___________________________________(4)(iii) What is the total resistance of the set of lights?________________________________________________________________________________________________________________________________________________________Total resistance = ____________________________(1)(b) How does the resistance of a filament lamp change as the temperature of the filament changes?________________________________________________________________________________________________________________________________________________________(1)(Total 7 marks)