Movie screens must be good reflectors. Why are polished mirrors NOT used for movie screens?

Question

PLEASE HELP ME ON THIS QUESTION!!!!

Answer 1

Mirrors reflect everything. If they used a mirror, the light from the projector will make an unwated glare and reflect audience members alike.

Answer 2

Just think it through.  Visualize your typical movie theater.  Replace the screen with black felt.  You already realize why that's not a good screen.  It absorbs all the light, so you see nothing.  Now replace it with a perfect specular reflector (a mirror).  What do you see?  It depends on where you sit, but it's an image of the rear of the theater with some of the side opposite you.  There's a bright spot somewhere, if that image happens to include the projector.  Now restore the diffuse reflector the theater actually uses.  The projector projects the movie image onto that screen.  At each spot, the screen reflects its incident light in all directions.  Wherever you sit, the top left corner is green.

You could design a movie theater where the 'screen' is a mirror, and the back wall is effectively a huge television screen.  But if you could do that, you'd simply replace that mirror with the actual television screen.

Answer 3

I agree with Meh. Incidently, movie screens don't reflect the image, they fix it!

Answer 4

Take a slide projector or digital projector and try to form an image on a bathroom mirror.  It is difficult to do because the light is reflected specularly (I didn't make up the term, I'm just using it).  What that means is that the light bounces off in a specific direction and unless your eyeball is sitting at the particular location to intercept the photons, you won't see them.  Therefore, you won't see an image.  What you do see, if your head is right in the direction of the specular reflection is the glare of the light source in the projector, but you won't see an image on the mirror.  

Forming images on a screen requires a defuse reflection, where there is no specular reflection.  Then your eye sees photons from all over the image area, not just those that are specularly reflected to your eyeball.

Google "specular diffuse reflection" for more details

Answer 5

You actually answered your own question:

You said "Movie screens must be GOOD reflectors" and that's true. You didn't say they must be PERFECT reflectors, which is what you'd have with a mirror.