DISPLACEMENT METHOD TO DETERMINE THE FOCAL LENGTH OF A CONVEX LENS

If the distance D of an object between an object and screen is greater than 4 times the focal length of a convex lens, then there are two positions of the lens between the object and the screen at which a sharp image of the object is formed on the screen. This method is called […]

DEFECTS OF VISION AND CORRECTION OF EYE DEFECTS USING LENS

The ciliary muscles control the curvature of the lens in the eye and hence can alter the effective focal length of the system. When the muscles are fully relaxed, the focal length is maximum. When the muscles are strained, the curvature of the lens increases and focal length decreases. For a clear vision, the image […]