Structures on a bird feather act like a reflection grating h

Structures on a bird feather act like a reflection grating having 8500 lines per centimeter. What is the angle of the first-order maximum for 552 nm light?

Solution

sin(theta) = m * lembda / d

d = 1 / 8500 = 0.000117 cm = 1.17 *10^-6 m

theta = sin^-1 (( 552*10^-9 /1.25 * 10^-6)

theta = 26.20 deg

so the angle of first order maximum is 26.20 deg