# Continuous absorption spectrum - why this happens?

1. Sep 6, 2011

### logearav

Continuous absorption spectrum -- why this happens?

1. The problem statement, all variables and given/known data

A pure green glass plate placed in the path of light, absorbs everything everything except green, similarly red glass plate absorbs everything except red.

2. Relevant equations
May i know the reason for this? Thanks in advance revered members

3. The attempt at a solution

2. Sep 6, 2011

### ehild

Re: Continuous absorption spectrum -- why this happens?

It is not true.
Seeing through, a glass plate if it absorbs red, appears green too. The complementary colour of green is red. If red is removed from white light we see green.

ehild

3. Sep 6, 2011

### logearav

Re: Continuous absorption spectrum -- why this happens?

My textbook on Spectroscopy mentions like this, but reasons are not given

4. Sep 6, 2011

### ehild

Re: Continuous absorption spectrum -- why this happens?

Your eyes work this way. The cones of your eyes see the colours. See: http://www.yorku.ca/eye/specsens.htm. Each kind of them are sensitive to a band of wavelength: one to red light, the other to green, the third to blue. If the incident light is red it activates the red cones and they send a signal to the brain: you recognise red color. If the red is missing from the incident light, the green and blue cones activate and you recognize it as some kind of green.
If the green is missing the remaining light activates the blue and red cones, and your brain recognizes it as some kind of red.

ehild

5. Sep 6, 2011

### logearav

Re: Continuous absorption spectrum -- why this happens?

Thanks for the reply Mr. ehid. But i am raising this question in spectroscopy perspective