Question

Question #0c3b8

Answer 1

`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)`.