Light and its reflection

Light is a form of energy which enables us to see the things around us. Objects can be seen only in the presence of light. In order to see any object, light from the object must reach our eyes. If no light reaches in our eyes then we cannot see anything around us. In the real sense light itself is not visible but it makes things visible. Some objects that have their own source of light, like the sun stars, candle, oil lamp, electric bulb, fire, glow, warm are luminous bodies. The non luminous object like table, chair, dust, blackboard, trees etc are visible to us when light from a luminous object falls on them and is reflected to our eyes.

Light travels in s straight line with very high velocity. The velocity of light is 300,000 kilometers per second. It is very fast that light can move from one place to another.

Reflection

We can easily see objects kept in light but we cannot see objects kept in a dark room. When light falls on the surface of the objects, some portion of the light may return to the same medium and falls on our eyes which enable us to see them. This phenomenon of returning of the light in the same medium is called reflection of light. Objects are visible due to reflection of light. If there was no reflection nothing could be seen. To be clear about we can take a small mirror and let the sunlight fall on it. Adjust the mirror to let the reflection light fall on wall of building. In this activity the ray of light falling on the surface of the mirror is called incident ray and the ray of light sent back from the surface mirror is called reflection ray.

There are two types of reflection. They are regular and irregular reflection. The amount of light reflected by an object depends upon its surface. Hard smooth and shiny surfaces are good reflectors of light. But rough and dull surface are poor reflectors of light. Depending upon the nature of surface on which light falls, there are two types of reflection highlighted as below;

1.       Regular reflection: when a parallel beam of light falls on a smooth or polished surface e.g. mirror, the reflected beam is also parallel to each other. Such kind of reflection is known as regular reflection. The direction of reflection depends on the position of the mirror. Due to regular reflection a smooth surface appears bright.

2.       Irregular reflection: when a beam of light falls on a rough surface e.g. wall, wood, paper, the reflected beam does not remain parallel but scatters. These types of reflection irregular reflection. Due to reflection the rough surface appears dull. Since irregular reflection occurs from the walls of a room, clothes, roads, vehicles, sky, tables, chairs etc and light after reflection reaches our eyes, these things are visible to us.