Fig. 8.1 shows a lamp from a car. It contains two metal filaments. [Figure 8.1 (car lamp with filament 1 and filament 2)]

1. (a)(i)Complete the boxes to describe the transfer of energy that takes place when the lamp is switched on. .......................................... energy and .......................................... energy [3][3]
2. (a)(ii)The efficiency of the metal filament lamp is less than 10%. State what is meant by efficiency. ............................................................................................................................................................................. ............................................................................................................................................................................. [2][2]
3. (b)The two filaments are usually connected in parallel to a car battery. A student investigates what happens when the filaments are connected in series, rather than in parallel. He uses the same battery for the investigation. State whether the current, the voltage across each filament and the total power produced increases, decreases or stays the same when the two filaments are connected in series. current ............................................................................................................................................................................ voltage ............................................................................................................................................................................ power ............................................................................................................................................................................ [2][2]
4. (c)(i)Fig. 8.2 shows the current–voltage graph for the two filaments. [Figure 8.2 (current-voltage graph for two filaments)] Calculate the total resistance of the two filaments when they are connected in parallel to a voltage of 12 V. resistance = ..................................................... [3][3]
5. (c)(ii)The two filaments are made from the same type of metal and have the same length, when uncoiled. They both operate at the same temperature. Suggest why one filament has a resistance that is greater than that of the other filament. ............................................................................................................................................................................. [1][1]
6. (d)Fig. 8.3 shows a relay used to switch on a car headlamp. [Figure 8.3 (relay diagram with pivot, iron armature, flexible contacts, switch S, headlamp H, iron core, coil of high resistance)] Explain why headlamp H lights up when switch S is closed. ............................................................................................................................................................................. ............................................................................................................................................................................. ............................................................................................................................................................................. ............................................................................................................................................................................. [4][4]

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