Physics (AS & A Level) · May / June 2016 · Paper 51 · Question 1

A student is investigating the characteristics of different light-emitting diodes (LEDs). Fig. 1.1 shows examples of LEDs and the circuit symbol for an LED. blue red circuit symbol: Fig 1.1 Each LED needs a minimum potential difference V across it to emit light. The student is investigating the relationship between V and the wavelength λ of the light emitted by the LED for several different LEDs. It is suggested that the relationship is V = kλn where k and n are constants. Design a laboratory experiment to test the relationship between V and λ. Explain how your results could be used to determine values for k and n. 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. [15] 3 Diagram 4 [Total: 15]

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