When we enter a completely dark room, nothing is visible to our eyes, but the moment we switch on the light, everything is visible. This is because light can be detected with the help of the human eye. It helps us to see things around us. Light is a form of energy without which we cannot see an object.
Beam of light
A straight line or path along which light travels is known as a ray. In general, it is an imaginary line used to show the direction of light. A group of light rays from a source is known as a beam of light.
A small slit on a door or a window facing the sun is opened in a dark room. Here, we can notice a beam of sunlight entering the room through the hole.
During power failures, light rays are visible when we switch on the torch. Even from the headlamps or headlights of two-wheelers, cars and trains, a beam of light can be seen.
The beam of the searchlight from the lighthouse is used to guide ships to the land, and in the airport tower, light beams direct the aeroplanes for landing in case of any failures.
Path of light
Light always travels in a straight line.
When you place a lighted candle at one end of the table, you can view it through a rubber pipe standing at the other end. But, you cannot view the lighted candle when you bend the rubber pipe since light travels in a straight line. A pinhole camera is a good example to show that the light travels in a straight line.
In a dark room, place a mirror at one corner and pass a direct beam of light from a lighted torch standing from another corner. You can now notice a patch of light falling on to the other side of the room. When you adjust the direction of the lighted torch, the patch of light from the mirror also changes its direction showing that light always travels along a straight line.
To study more about the basics of light, click here.