LAUSR

In this experiment we have first determined the focal length of an equiconvex lens. We have observed that a real image can be formed by the lens on the same side of the source if the source is sufficiently strong. This is due to the reflection from the concave surface of the lens. We have measured these image distances for different object distances. From these measurements, we have determined the refractive index of the lens as well as its radii of curvature. The relationship between the object and image distances in the reflection from the concave surface of a lens as formulated here, is similar to the ordinary reflection from a concave mirror. However, the focal length, in this case, turns out to be smaller than that of a regular concave mirror of the same radius of curvature by a factor of two, for a lens of refractive index of 1.5.