Question #0c3b8

1 Answer
Feb 26, 2017

theta_(red) should be greater than angle theta_(blue) - see below.

Explanation:

We know for the grating that:

d sin theta = n lambda, see below for meaning of terms in this equation.

For constant slit width d and looking just at the first maximum at n = 1, we see that for angle theta to normal:

theta = arcsin( lambda/d)

If we use the following wavelengths, ie lambda's, as being indicative:

  • lambda_(red) = 650 nm

  • lambda_(blue) = 475 nm

.... then it follows that angle theta_(red) should be greater than angle theta_(blue) .