Question

400nm light strikes a disguising grid 10000 lines / cm.
a. determines the angular separation of the first and second maximum from the center

b. if the light that falls outside of 700nm determines the angular separation of the first and second maximum from the center. Explain what happens with the second order in this case

Answer 1

I will find the separation in degrees as well as in radians as question does not specify.

first, we need to find d

d = 1 / 100 * 10000

d = 1e-6 m

Now,

we know

d*sin = m

for first maximum, m = 1

therefore,

sin = 400e-9 / 1e-6

= 23.57 degree or 0.4115 radians

Now, for m = 2

sin = 2* 400e-9 / 1e-6

= 53.13 degree or 0.927 radians

therefore angular separation is 29.56 degree or 0.5159 radians

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What do you means be "if the light that falls outside of 700nm"

does this mean if wavelength is like 800 nm or 900 nm or so on

then follow the same procedure. However, you will notice that second maximum is not possible with wavelengths outside 700 nm