6A20.41 Projected Candle with Mirror


Image formation, concave mirror


A concave mirror projects the image of a lit candle. A hand or small metal sheet can be used to block parts of the candle or mirror to test knowledge of image formation.



  • [1] Candle
  • [1] Concave mirror
  • [1] Lighter or box of matches
  • [1] Sheet of metal 

Classroom Assembly

  1. Place the equipment away from things that easily burn, like paper.

Important Notes

  • Be careful not to burn anything other than the candle!
  • Beware of hot wax!


  1. Light the candle.
  2. Place the mirror so that it projects a candle image on the wall.
  3. Ask students what will happen when you start blocking the candle from the bottom.
  4. Block the candle from the bottom, showing it blocks the image from the top, so the image is inverted. Block the candle from the top for further emphasis, if desired.
  5. Ask students what will happen when you start blocking the mirror from the bottom.
  6. Block the mirror from the bottom, dimming the image.
  7. Blow out the candle.


Additional Resources


  • PIRA 6A20.41


  • Don't attempt this at home!

Last revised

  • 2017


Related AV

Related demos

  • Filament Projection with a Lens


If you have any questions about the demos or notes you would like to add to this page, contact Ricky Chu at ricky_chu AT sfu DOT ca.