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) #.