Gallery 2

Light Harp

Digital technology using lights, light sensors and a computer are combined to play music on this virtual instrument.

How it works

Block beams of light with your hands to trigger sensors and play digital music.

Things to try or ask around the exhibition

  • What's the maximum number of notes that we can play at once by blocking the light beams?
  • How quickly should we block the light beam to get notes in quick succession?
  • Would it be easier to play the Light Harp with small hands or large hands?


Light shines from Light Harp's top frame onto light sensors found inside deep holes along the bottom frame. Light travels in straight lines, so only light that shines directly above each light sensor will be detected.

When you break each light beam with your hands, light is blocked from reaching a sensor. As a result, the sensor sends a signal to a computer to play a musical note. The computer contains samples of pre-recorded instruments, such as an actual harp, or a piano.

Finding the science in your world

Light instruments similar to Light Harp are used by some musicians to perform music as part of a concert.

Some security alarm systems also use technology where, if a person breaks a light beam with their hand or body, sensors detect the absence of light and set off an alarm.