2. Light waves of the wavelength of 650 nm and 500 nm produce interference fringes on a screen at a distance of 1m from a double-slit of separation 0.5 mm. Find the least distance of a point from the central maximum where the bright fringe occurs due to both sources coincide? 3. Suppose (100), (110) and (111) are three simple cubic lattice. Find the ratio of the lattice the separation between the successive planes of these crystals.

Light from two different sources are incident upon the same side of a polarizing filter. light from one source is polarized with total intensity ip, while light from the other source is unpolarized with total intensity iu. as you rotate the polarizing filter through 360 degrees, the intensity of the transmitted light on the other side varies by a factor of 9. what is the relative intensity of the initial polarized source to the unpolarized source, or ip/iu?