Physics 9702/53 — May/June 2016

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.

Each LED needs a minimum potential difference $V$ across it to emit light. The student is investigating the relationship between $V$ and the wavelength $\lambda$ of the light emitted by the LED for several different LEDs.

It is suggested that the relationship is

where $k$ and $n$ are constants.

Design a laboratory experiment to test the relationship between $V$ and $\lambda$. 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.