(ii) Draw a suitable graph on graph paper to show how the current varies with potential difference. (12)
(iii) Use your graph to calculate the resistance of the bulb when the voltage is 2 V and again when it is 10 V. (10)
(iv) Explain why the resistance of the bulb changes as the voltage increases. (6)
Q4 A student carried out an experiment to investigate the variation of current I with potential difference V for a copper sulphate solution.The table below shows the data obtained.
Table 18.8 V / V I / mA
1.0 29
2.0 61
3.0 96
4.0 120 5.0 157 6.0 181 7.0 214
(i) Draw a suitable diagram of the apparatus used in this experiment, identifying the anode and the cathode.
(ii) Draw a graph, on graph paper, of the current against the potential difference.
(iii) Calculate the slope of your graph and hence determine the resistance of the copper sulphate solution. (Assume the resistance of the electrodes is negligible.)
(iv) Draw a sketch of the graph that would be obtained if inactive electrodes were used in this experiment.
Q5 A student investigated the variation of the resistance R of a metallic conductor with its temperature . The table shows the measurements recorded by the student. Table 18.9
/ C 20 R / 9.8
30 10.2 40 10.5 50 10.8 60 11.3 70 11.6
80 12
90 12.5 (i) Describe, with the aid of a labelled diagram, how this investigation was carried out.
(ii) Draw a suitable graph to show the relationship between the resistance of the metal conductor and its temperature.
(iii) Use your graph to estimate the resistance of the metal conductor at a temperature of 0 C.
(iv) What does your graph tell you about the relationship between the resistance of a metallic conductor and its temperature? Justify your answer.
(v) Why is the wire submerged in glycerol rather than being placed directly in the water? (vi) State another precaution that should be taken to ensure the accuracy of this investigation.
