if you have some laser light or a torch you must have seen whenever you turn it on in a dark room the light is visible. that's visible due to scattering of light due to Dust particles present in the room.
When a beam of sunlight enters the dark room through small hole or window then its path become visible due to scattering of light by the dust particles present in the room. 2. When a beam of light is projected on a screen from a projector in the cinema hall, it becomes visible.
