pls. tell why do we use a lens of shorter focal length to read small letters instead of higher focal length??
A magnifying glass (called a hand lens in laboratory contexts) is a convex lens which is used to produce a magnified image of an object. The lens is usually mounted in a frame with a handle (see image).
A magnifying glass works by creating a magnified virtual image of an object behind the lens. The distance between the lens and the object must be shorter than the focal length of the lens for this to occur. Otherwise, the image appears smaller and inverted, and can be used to project images onto surfaces.
Hope this helps.