Home Candle in Water Materials & Instructions
Candle in the Water
Have you ever wondered why you can see your own face in the night passing in front of a dark store window in a lit street, yet you won’t see you face in the light of day?
Pepper’s Ghost demonstrates this phenomenon. In the late 19th Century, a London showman named John H. Pepper used a stage with a transparent window at an angle to the audience to display ghostly reflections of off-stage actors. The actors on stage behind the transparent window could ‘walk through ghostly images’ which could appear and disappear to produce unexpected effects.
A simple way to build and create Pepper’s Ghost is by creating a small black box like the one you see under you. Using simple materials such as wood, Plexiglas, black paint, a paper towel roll, and an electrical candle, one can be a magician just like Pepper himself, causing the image of the candle to appear in water.
Directions:
1. Make sure electrical candle is placed in front of box, and in line with the glass of water inside the black box.
2. Turn on electrical candle.
3. Look at the assembly from the front ~ you should be able to see a virtual image of the candle burning in the water!
4. Turn off the electrical candle when done gawking at this most extraordinary craftsmanship. Thank you.
Physics Explanation:
When light travels from one medium to a different medium, part of the light is transmitted and part is reflected at the interface (or boundary). The relative amount of transmission and reflection depends on the ratio of the refractive indices (indexes) of the tow media as well as the angle of incidence to the interface. When the candle hits the Plexiglas, about 8% of the light is reflected back to our eyes, and 92% is transmitted through the Plexiglas; we do not see this because we are not inside the box. There is no light transmitted from behind the Plexiglas since the box is painted black. Therefore, the light that can reach our eyes is only the reflected candle light.
Why is it important to paint the box a dark color? If it was white then 96% of the white would be transmitted through the Plexiglas and only 4% would reach our eyes. This transmitted light would be in competition with the weak reflected candle light.