- Do this experiment in the dark room.
- Take a prism and place it on a table near a vertical white wall.
- Take a thin wooden plank.
- Make a small hole in it and fix it vertically on the table.
- Place the prism between the wooden plank and wall.
- Place a white light source behind the wooden plank.
- Switch on the light.
- The rays coming out of the hole of plank become a narrow beam of light.
- Adjust the height of the prism such that the light falls on one of the lateral surfaces.
- Observe the changes in emerged rays of the prism.
- Adjust the prism by slightly rotating it till you get an image on the wall.