(a)(i) In polarization vibration of wave is in one plane while interference is an effect produced when two-waves of the same wave length or amplified or frequency travelling in the same direction in a medium are super imposed. (ii) Only transverse waves can be polarised while in interference both transverse and longitudinal waves are involved. (b) Uses of polaroids are in: - sunglasses - Polaroid cameras - Products on the 3-dimensional films, and - determination of sugar solution concentration.