Te Reo Physics Resources

Multimedia Physics and Science Teaching Resources


Candle Under Water | Te Mura Raro Wai


A ghostly candle appears to burn under water using a thinly-silvered mirror.

Principles Illustrated
Formation of virtual images by a mirror, reversibility of light rays, “one-way” mirrors that are not “one-way” at all.



English version

Te Reo Māori Version

English version

Te Reo Māori Version


Set up beaker inside box and candle outside. Fill the cylinder, asking students if the candle will go out when the water level rises too high. They say that it will not go out. As the water level rises to the flame height, blow out the candle. This will surprise the students. Then relight the candle and show the flame under water. See movies below. Students enjoy this one!
If time permits, have students look through the “one-way” mirror from each side. From one sees the cylinder through the mirror and from the other direction one sees the candle through the mirror. It passes light in both directions. So how does it work? How does it give the one-way effect? See one-way mirrors and strange reflections.

Candle Under Water
Photo of candle appearing to burn under water.
Candle Under Water Sketch
Sketch of apparatus.

Other Information


Watch flames and matches! The candle never goes inside the box.
Individual teachers are responsible for safety in their own classes. Even familiar demonstrations should be practised and safety-checked by individual teachers before they are used in a classroom.

He Kōwhai Rūkahu? (Is it Really Yellow?), Kitenga Tae (Seeing Colours), Te Kokinga o te āhea o Ngā Whatu (Eye Resolution).
See also one-way mirrors and strange reflections

Notes, Applications, and Further Reading

This demonstration is related to PIRA 6A10.60.


This teaching resource was developed by the Te Reo Māori Physics Project with support from