Light Travels in Straight Line
Light travels in a straight line or curved line, that is a common question for all of us. Many times we all are confused. In this chapter, we discuss all light paths along with proof.
Let’s start an interesting lesson, about Light Path as well as to understand light travels in a straight line. Do you love to ride a bicycle? When you ride your favorite bicycle, you can go on a straight road or you can go on a curved road as well. In the same way, do you know light also travels in a light path?
Let us consider, you are in a dark room at day time. How do you make a dark room in a day time, when the sunlight is there! It is very simple! Close all the areas through which light is coming.
Make sure, the following things:
Now, no light is coming into the room by any means and the entire room is very dark.
Now, are you able to see anything?
No, because the light is obstructed to enter into the room. If you open the window slightly, you will see light is coming to the room. Even if, you are opening a very tiny space, a beam of light enters the darkroom.
From these light beams, we are able to see that, light travels in a straight line.
If you switch on your torch light, in a dusty area, you will see a straight beam of light along with white dust. Light beam means a bunch of light rays for simple understanding.
Refer to the below image for light on a dusty area
You can switched on you light in dusty are to check how does light travels exactly!
Based on all our examples, it seems light to travel along a straight line.
Now, we will try to understand from a very simple example. Take the following things:
We will check the two conditions.
Let’s lit the candle and take the pipe. Make the pipe straight and see the candle through the pipe. Now, are you able to see it?
We are able to see because the light comes to our eyes through the straight pipe. Hence, we can say, the light may go straight to a straight line.
Now, we will make the pipe bend.
If we bend the pipe. Do you think you can see the candle?
We are not able to see because light can not come to our eyes through this curved pipe. Again, if make the pipe straight, then we can see it again.
We know, we can see any object, when light ray comes from it and reach our eyes.
Hence, it can be said that light can pass through a straight pipe only.
Check out our ANIMATED video!
We will prove that light travels in a straight line.
The path of light can be easily proved by putting an object on its path. We will take a few accessories to prove it. These are:
Take these three cardboards and make holes in the middle of each cardboard with the help of a pin. Now, how do you make a hole in the middle of the cardboard? Is it difficult?
No, not at all. It is simple!
Based on the marking of all three cardboards, make the holes with the help of the pin.
All the cardboards should be placed vertically with the help of the clay. Take little clay and fixed it at the base of the cardboard. Make sure, the following three points,
Now take a candle and place it on one side. make sure, the height of the hole of cardboards and the tip of the candle are the same. And try to look tip of the candle from the opposite side. Are you able to see the tip of the candle now?
Yes, you can see it because the light travels through the holes and reaches your eyes.
Now if we displace the cardboard kept in the middle, and observe then we can not see to see the flame of the candle. Why does it happen? Why we are not able to the flame now? Because the light gets blocked by the cardboard.
Since the light could not travel the curved path we can not see the candle. If the light could have traveled a curved path, we could have seen the candle. Now, if we change the cardboard in the previous position so that all the holes are in a straight line, then again we will see the light.
Hence, it is clear that light travels in a straight line only. This is one of the main properties of light and it is most commonly known as rectilinear propagation.
To check it clearly, we will draw lines between candle tip, and holes, and eye. We will see this drawn line is in a straight line. Hence, we can say, light travels in a straight line.
Hence, we have learned the basic understanding of light path along with a small experimental set and proved that light travels in a straight line.