Activity to show that light travels in a straight line

1. Place a candle on one end of the room and take a rubber tube.
2. Stand on the other end of the room and view this candle with the help of the tube.
3. 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.