# Diffraction Grating

• May 21st 2008, 05:32 AM
Ant
Diffraction Grating
hi,

When white light it diffracted through a diffraction grating I understand that it is split up into a spectrum of all the colours (as each wavelength is diffracted a different amount). But why does red light (which has the largest lamda) appear furtherest away from the centre maxima? Why is red light diffracted the most?

any help very much appreciated!
• May 21st 2008, 06:17 AM
colby2152
Quote:

Originally Posted by Ant
hi,

When white light it diffracted through a diffraction grating I understand that it is split up into a spectrum of all the colours (as each wavelength is diffracted a different amount). But why does red light (which has the largest lamda) appear furtherest away from the centre maxima? Why is red light diffracted the most?

any help very much appreciated!

Smallest frequency, i.e. longest wavelength...

http://mindprod.com/image/screenshot/wavelength.png

Questions like these can be answered in the new, MHF affiliated Physics Help Forum.
• May 21st 2008, 09:42 AM
Sean12345
If you think about the equation relating the angle from the centre a maximum occurs and wavelength;

$sin~\theta ~=~ \frac{\lambda}{d}$

As mentioned by colby red light has a larger wavelength, thus the value for $sin~\theta$ and consequently the value for $\theta$ is larger.