6A10.60 Candle in a Beaker of Water
Concepts
Reflection, plane mirrors, transmission
Overview
A candle appears to be underwater by superimposing the transmitted light from the beaker with the reflected light from a candle. A pane of glass between the candle and the beaker acts as both the transmission medium and the mirror.
This illusion is also known as Pepper's ghost.
Details
Equipment
- [1] Beaker
- [1] Container of water
- [1] Candle
- [1] BBQ lighter or book of matches
- [1] Black fabric
- [1] Desk lamp
- [1] Black metal plate
- [1] White background on a stand
- [1] 2-poled lab stand
- [2] 90-degree clamp
- [1] Pane of glass
- [2] Magnet
- [1] Camera
- [1] Fire extinguisher
Classroom Assembly
- Attach the 90-degree clamps and magnets to the lab stand to make a holder for the pane of glass. Put the glass in.
- Place the candle and beaker such that they overlap.
- Use the metal plate to block the candle from the audience and block stray light sources.
- Adjust the lighting as desired using the black cloth, white background, and the desk lamp.
- Focus and zoom the camera on the beaker. Ideally, the field of view doesn't show any edges of the glass.
Important Notes
- Do not place the black fabric anywhere above the candle. The fabric can melt or catch fire.
- Fire is dangerous. Do not run this experiment near anything highly flammable. Be prepared to evacuate, if necessary.
- Remember you have a fire extinguisher if an uncontrolled fire starts. Refresh yourself with the fire extinguisher controls, if necessary.
Script
- Turn off the room lights.
- Activate the camera.
- Light the candle.
- Point out the candle "inside" the beaker.
- Pour water into the beaker so that the candle appears submerged.
- Blow out the candle and explain the actual arrangement of the objects in the demonstration. Explain the illusion is sometimes used in stage productions or carnival attractions.
Additional Resources
References
- PIRA 6A10.60
Disclaimer
- Don't attempt this at home!
Last revised
- 2022
Technicals
Related AV
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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.