A student sets up the circuit shown in Fig. 11.1. R is a fixed resistor in the circuit. The filament lamp is marked 12V, 0.25 A. The circuit is used to produce a current/voltage graph for the filament lamp. The ammeter and voltmeter needed are not shown. To obtain different readings, the student changes the position of the movable contact. [Figure 11.1]

1. (a)On Fig. 11.1, draw the symbols for an ammeter and a voltmeter in the correct positions.[3]
2. (b)Explain why it is sensible to include the resistor R in this circuit.[2]
3. (c)(i)On Fig. 11.2, sketch a current/voltage graph for the lamp. [Figure 11.2][3]
4. (c)(ii)State and explain how a current/voltage graph for a fixed resistor is different from the graph for a filament lamp.[2]
5. (d)(i)Fig. 11.3 shows the position of the movable contact when the voltage across the lamp is 12V and the current in the lamp is 0.25 A. Determine the current in the 50Ω resistor, [Figure 11.3][2]
6. (d)(ii)Determine the current in R,[1]
7. (d)(iii)Determine the potential difference (p.d.) across R,[1]
8. (d)(iv)Determine the resistance of R.[1]

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