Explain light travel in straight in …

Life without light would have been pretty dull. Light travels at a speed of 186,000 miles per second. You must have observed that in your house that whenever a beam of light enters a dark room through a tiny hole in the window, the lightwave always travels in a straight line.

Let us carry out a small activity to show that lightwave travels along a straight line. Take three CD’s and align them together. Align them in such a way that all the CD’s line in a straight line. Now take a candle and place it at the other end. Do make sure that the tip of the candle and the holes of the CD’s all lie in the straight line. Ensure that the height of the CD’s and the tip of the candle are same. Observe the flame of the candle. We are able to see the flame of the candle because the light wave travels through the holes and reaches our eye.

Now if suppose we displace the center of the CD’s we observe that we are not able to see the flame of the candle. Why does that happen? This is because the light gets blocked. If the light could have the ability to take a curve and travel, we could have seen the lightwave. But since light travels in a straight line, we were unable to see the flame of the candle when the CD is displaced. This proves that light travels along a straight line

In the above picture, we can clearly see that light coming through the holes in the window travel along a straight line