Fig. 9.1 is the current-voltage graph for a filament lamp. [Figure 9.1]

1. (a)Fig. 9.2 shows an incomplete circuit diagram of the circuit that a student uses to obtain the readings for the graph. [Figure 9.2] Complete the circuit diagram using suitable circuit symbols for the lamp, a voltmeter and a variable resistor.[3]
2. (b)The ammeter used by the student has ranges 0-10A, 0−1A, 0-100mA and 0-10mA. Describe how the student uses the different ranges to obtain readings which allow all nine points to be plotted precisely on the graph while using the ammeter safely.[2]
3. (c)State how Fig. 9.1 shows that the lamp does not obey Ohm's law.[1]
4. (d)(i)Using Fig. 9.1, determine the resistance of the lamp when: the voltmeter reading is 0.40V resistance =[1]
5. (d)(ii)the voltmeter reading is 6.0V. resistance =[1]
6. (e)(i)Explain why the resistance of the lamp changes as the voltage changes.[2]
7. (e)(ii)State how the resistance of a wire depends upon its length and how it depends on its cross-sectional area. length cross-sectional area[2]
8. (e)(iii)The student obtains a long sample of the same type of wire as the filament in the lamp. The wire he obtains has the same cross-sectional area as the filament. He cuts a 1.0m length of the wire and measures its resistance at room temperature. He obtains the value 16Ω. Using the appropriate resistance value from (d), estimate the length of the filament wire in the lamp. length =[2]

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