Physics (AS & A Level) · May / June 2021 · Paper 51 · Question 1

A student investigates the current in a coil and a resistor connected in series, as shown in Fig. 1.1. R coil Fig. 1.1 The student connects a high-voltage d.c. power supply and a switch across the series combination. When the switch is closed, it takes time t for the current in the resistor of resistance R to reach a maximum value. The time t is a few milliseconds. There are a number of different unmarked resistors available. It is suggested that the relationship between t and R is t = KN2A LR where N is the number of turns of wire on the coil, A is the cross-sectional area of the coil, L is the length of the coil and K is a constant. Design a laboratory experiment to test the relationship between t and R. Explain how your results could be used to determine a value for K. You should draw a diagram, on page 3, showing the arrangement of your equipment. In your account you should pay particular attention to: ● the procedure to be followed ● the measurements to be taken ● the control of variables ● the analysis of the data ● any safety precautions to be taken. 3 Diagram 4 [15]

Read automatically from the paper; the printed page above is exact.