In an experiment, light of wavelength 600 nm falls on two slits which are spaced at a distance of .5 mm. The resulting interference pattern is such that the spacing between the first and second dark fringes is 6 mm.
a. What is the distance of the slit to the screen?
b. How will the spacing between the first and the second dark fringes change, if the of wavelength 500 nm is used in the above experiment?