Question

Ordinary white passes through a diffraction grating having 10,000 slits per centimeter, i.e. a slit separation of d = 1.00 X 10-6 m, and casts a diffraction pattern on a screen. You measure the angular separation between the central white fringe and the blue stripe in the first (m = 1) rainbow as 23.6 degrees. From this information, calculate the wavelength of blue light.