Light of wavelength 400 nm (in vacuum) is incident on a diffraction grating that has a slit separation of 1.2 x10-5 m. The distance among the grating and the viewing screen is 0.10 m. A diffraction pattern is produced on the screen that consists of a central bright fringe and higher-order bright fringes (see the drawing).
(a) Decide the distance y from the central bright fringe to the second-order bright fringe.
(Hint: The diffraction angles are small enough that the approximation tan(θ) ~sin(θ) can be used.)
b) If the entire apparatus is submerged in water (nwater= 1.33), what is the distance y?