6B10.30-Paraffin block photometer

6B10.30-36B10.30-1 6B10.30-2

Watch this demo

Description: This demonstration gives a visual metric for how light intensity changes with distance


  • Paraffin block photometer
  • Clamp on light
  • VariAC
  • Light bulb
  • VariAC to banana plug cable

Setup Procedure:

  1. Clamp a light to the end of a table.
  2. Connect the light bulb to the VariAC.
  3. If a new photometer must be made, take two bars of paraffin was, place a piece of aluminum foil in between them and tie together with rubber bands.

Demonstration Procedure:

  1. Turn on both lights.
  2. By holding the photometer so that each wax block is facing a light source, you can compare the intensity of the light from two sources.
  3. You may also vary the distance between sources and show that the intensity follows the inverse square law (use one light as a reference source).
  4. When finished, turn off both lights.

Note: Don’t place the Paraffin block photometer near any hot light sources, as the wax may melt.