Physics (AS & A Level) · Feb / March 2019 · Paper 52 · Question 1

A student is investigating the behaviour of a capacitor-resistor circuit as shown in Fig. 1.1. input output R C Fig. 1.1 A neon lamp flashes on and off when it is connected across the capacitor with a potential difference VF across the lamp of approximately 90 V. The student has a number of unmarked resistors. It is suggested that the period T of the flashes of the lamp is related to the resistance R of the resistor by the expression T = RCK where C is the capacitance of the capacitor and K is a constant. The constant K is given by K = ln  Vi – VL Vi – VF where Vi is the potential difference across the input, VF is the potential difference required to make the lamp flash and VL 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 and VL. 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.