Q1 In an experiment to measure the resistivity of the material of a wire a student measured the length, diameter and the resistance of a sample of nichrome wire.
The following data was recorded. resistance of wire zero error on
micrometer length of wire
diameter of wire
27.1 0.02 mm 86.5 cm 0.26 mm 0.24 mm 0.25 mm 0.23 mm 0.25 mm
(i) Describe how a micrometer is used to measure the diameter of the wire. Include reference to the zero error.
(ii) Calculate the resistivity of nichrome using all the data provided.
(iii) Describe the procedure used in measuring the length of the sample of wire. (iv) Why did the student measure the diameter of the wire in a number of different places? (v) State one other precaution taken to ensure the accuracy of this experiment.
(12) (15) (6) (4) (3)
Q2 In an experiment to investigate the variation of current I with potential difference V for a length of nichrome wire, the following results were obtained.
Table 18.6
V / V I / A
1 0.08 2 0.15 3 0.23 4 0.31
(i) Draw a suitable circuit diagram used to obtain this data. (ii) Describe how the student varied the potential difference.
(iii) Using the above data, plot a graph on graph paper of current against potential difference for the wire.
(iv) Referring to your graph, discuss how the current varies with the potential difference.Your answer should make reference to Ohm’s law and the resistance of the component.
5 0.39 6 0.46
(12) (4)
(12) (12)
Q3 A student carried out an experiment to measure the variation of current with potential difference for a filament bulb.The following data was recorded.
Table 18.7
Potential difference / V 1.5 Current / A
0.9
3.0 1.7
4.5 2.3
6.0 2.8
7.5 3.1
9.0 10.5 12.0 3.3
3.5 3.6
(i) The circuit diagram in Fig 18.33 on the next page was used in the investigation. Name the apparatus X,Y and Z and state the function of each.
