How an experiment that show how light travels in a straight line?

Answer 1

In Mathematics, a straight line can be drawn if at least two points are given. If three points have to be in the same line, then line joining any two points of them must pass through the third one. So it will be sure to establish the straight line traversal of light radiation by at least three holes. So three card boards with holes made at the same height are kept on a table. On one side a light source, say a glowing bulb, is placed. Adjusting the position of the card boards the light could be made visible at the other side. If suppose we disturb any one the card boards, then light becomes invisible. Hence it proves that light traverses in a straight line.

Hint: With the card boards kept in the right position, even when we displace the candle laterally and slightly light will be seen without fail. So two card boards will not be enough to establish the straight line traversal of light. At least three are a must.

Answer 2

To demonstrate how light travels in a straight line, you can set up a simple experiment using a straight tube with a small hole on one end. Shine a light source through the hole and observe the straight line of light that emerges on the other side. You can also use mirrors to reflect the light and show its straight path. This shows that light travels in straight lines unless it encounters a medium that causes it to refract or reflect.