Question

Suggest two ways by which we can get light of a single colour to fall on the screen after passing through a prism

Answer 1

After the white light has passed through the prism you have a spectrum coming out of a different edge. Now you could superimpose a screen with a single slit over that spectrum, centering the slit on the color your want.

Alternatively, you could use a filter (e.g., red tinted glass or cellophane) to select for one color.

Answer 2

I understand the slit thing, making the space too small for any other of the colors to come out, but I don't understand the filter. Could you explain a bit?

Answer 3

Here's a picture

Answer 4

Notice the question doesn't say a single frequency, but just a single color. So the red filter in this diagram would work.

Answer 5

so, when all the colors make white, going through the translucent red glass or cellophane
I see

Answer 6

Thanks

Answer 7

Do a google search of "red filter", and you'll see it's quite common in photography. You can also use filters of other colors.

Answer 8

Crud... I see now that it's common sense, I've been googling how the heck to get one color to come out of a spectrum by itself for almost an hour