Oscillating String
Light Sound and Waves

TV Strobe Light

Enrichment Activity for 5-11 11-14

What you need

  • A cathode ray tube television (turned on!)
  • A rubber band


  1. Stretch the rubber band between your thumb and first finger
  2. Holding the band between you and the television screen, pluck one side

Results and Explanation

You should see the band make zig zag shapes. The television picture is made up of tiny dots flashing on and off. It acts like a strobe light, freezing the band's vibrations at different positions so it looks like it's moving in slow motion.

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