16. Determination of h using LEDs

  • 00:50 Rearrange the equation to show that h equals 5.333 x 10-28 divided by the gradient of the graph.
  • variable d.c. power supply

  • 1 kΩ protective resistor

  • voltmeter (resolution ± 0.01V) [multimeter set to appropriate range]

  • connecting leads

  • various LEDs – with known wavelengths

Hazard Risk Control measure


Heat – the components will get hot if the power is left on.

Students should wear eye protection and should only connect the power when taking measurements.