how can you show that light travels in a strait line - Science - Light Shadows and Reflections

Question

how can you show that light travels in a strait line

Hansraj Rai · Accepted Answer

Take 30 cm long pipe having small diameter of the cross section
and place a candle at one end of the pipe Now look through the
other and of the pipe You can see the candle
Now bend the pipe and look through the same end, at this time
candle is not visible This shows that the light travels in a
straight line