Why are cinema screens made white and rough?
Answer: As the cinema screen is rough, defused reflection occurs by the incident light on the screen. As a result, the reflected rays spread around the hall, i.e. reaching the eyes of every spectator. That is why the audience can see the picture from any place in the hall. Hence, the movie screen is made rough.
As the cinema screen is white, it does not absorb the incident light but reflects almost the entire part. So the picture looks brighter on the white screen. Also, because the white screen reflects all colours of light, the colour of the image does not change. Hence, the movie screen is whitened.