Simple Optics Question

There was a question on my exam. There is a green filter and blue light is directed to the filter. Normally It should pass through the blue light but my teacher says that we wouldn't be able to see it so the color we see would be black but I think it would be blue. What is the answer?

blue_leaf77
Homework Helper
Usually, when people talks about [color] filter, such as green filter, then they mean a filter which visually appears [color]. So in your case, green filter should appear green. This means this filter only let through frequencies corresponding to green colors and block other frequencies.colors.

For an ideal green filter, with just a narrow band pass, the blue light will no go through.
For a real, usual filter (like the ones used in photography), some of the blue will go through.

sophiecentaur