Homework Help: Separation of two wavelengths in a diffraction grating.

1. May 9, 2010

borvis

1. The problem statement, all variables and given/known data
Light with two wavelengths (510.0 nm and 525.6 nm) is spread by a diffraction grating. On a screen 4 meters behind the grating we observe that the diffrence between the two second order maximum is 1 cm. What is the grating constant (d) ?

2. Relevant equations
I think i only need Snells Law for this problem, and some geometry.

3. The attempt at a solution
Im having som problem with the geometry of the solution. I need to find the distance to one of the maximums from the zero order maximum. Ive found the relations:
sin(a)=($$\lambda1$$/$$\lambda2$$)*sin(b)

2. May 9, 2010

nickjer

Snell's law? You might want to use the formula for maxima's of a diffraction grating:

$$d \sin \theta_m = m\lambda$$