Question

With the help of an experiment, prove that light always travels in a straight line.

Answer 1

Light travels in a straight line. This is called the rectilinear propagation of light. This can be observed by a simple experiment: light a candle and place it on a table. Take a pipe that is straight and observe the flame of the candle through it. The flame can be clearly seen through the pipe. Now, try to see the flame of the candle through a bent pipe. The flame cannot be seen through it.
This experiment demonstrates the rectilinear propagation of light.