Light of wavelength 5.0*10^-7 m in air is incident normally (perpendicular) on a doubled slit. The distance between the slit is 4.0*10^-4 m, and the width of each slit is negligible. Bright and dark fringes are observed on a screen 2.0 m away from the slits.

A) Caculated the position of the first antinode (bright fringe) on the screen.

B) Caculated the position ofthe second node (dark frine) on the screen.

C) If the distance between the slits is decrease by a factor of ten then the position of the first antinode will be greater than, less than or same as the position caculated in part A. Vertify your response with calculation.

Using the same set up as before but replacing the double slit with diffraction grating a first order antinodes is found 0.5 mm above the central antinode.

D) Caculate the line density in slits/mm of the diffraction grating.