- Place a candle on one end of the room and take a rubber tube.
- Stand on the other end of the room and view this candle with the help of the tube.
- Bend the pipe a little and then try to see the candle.
It will be observed that we are able to see the candle using a straight tube , but when the tube is bent, the candle is not visible.
This shows that light travels only in straight lines.