7A10.10 – Photoelectric Effect with Neon Bulb

Watch this demo

Description: This shows the photoelectric effect using an Neon bulb and UV light.


  • Variac
  • 2 alligator clips
  • UV light source
  • Flashlight
  • Neon bulb

Setup Procedure:

  1. Plug the variac into the wall
  2. Attach the alligator clips to the banana clips attached to the variac
  3. Attach the alligator clips to each end of the neon bulb
  4. Set the variac power to just under the power needed to light the bulb

Demonstration Procedure:

  1. Power the variac on
  2. Shine the UV flashlight on the neon light, and the neon light should shine
  3. When finished, turn off the UV light and the variac

Notes: If you shine the UV light on a powered neon light, the light will interact with the Neon according to the Photoelectric effect, exciting electrons that will emit photons.