This video lecture from Optical Instruments (F.Sc. first year physics) covers Lens, Types of lenses, Difference between lens and mirror and derivation of formula for lenses. Also you will learn that how this formula is used in microscopes and telescopes and in other purposes. Find more e-learning material and educational video lectures in Urdu at maktab.pk. These videos are free to use for promotional and commercial purpose by keeping the credits to Maktab.