rencontre ulla avis In this video lecture I have discussed about the Length Contraction. To understand it the basic information about the two transformations (Galilean and Lorentz) are important. It is based on the basic concept of Frame of References, here two frames S and S’ are considered. S’ frame is a moving frame with respect to the S and moving in the positive X direction with the relative velocity v. O and O’ are two observer in S and S’ frame respectively, and P is any event that occur in S’ frame. here we have consider the rod of length l0 that is placed in a moving frame, its length appear l in S frame. By using the Lorentz transformation I have shown here the relationship between the l and l0. The two different observations of the two observers.