Definition: Light is a form of energy, which induces the sensation of vision in our eyes and makes us able to see various things present in our surrounding.
Units Of Light: Any object which has an ability of producing light energy at its own is called as the source of denoted by letter “d”.
Source Of Light: Any object which has an ability of producing light energy at its own is called as the source of light. e.g., Sun, Firefly, Battery, Cell Candle, Bulb etc.
Kinds Of Sources Of Light:
There are two main kinds of sources of light viz:
1) Natural Sources:- These include all those sources which are natural and possess their own light for example stars, firefly etc.
2) Artificial sources:- These include all those sources which are man-made or artificial but possess the ability of emitting light for example candle, lantern, moon etc.