A simple convex lens having a small focal length is called a magnifying glass or a simple microscope.
It is based on the principle that a convex lens produces an erect and highly magnified image of the object when it is placed between the principle focus and the optical centre of the lens.
The lens is so adjusted so that the image is formed at the least distance vision (25cm).
When a convex lens is placed near a piece of small object, we can observe the enlarged image of the same object as shown in the figure.�� This particular process is known as magnification.
Magnifying lenses are used for making spectacles.
People suffering from far-sightedness are generally advised to use magnifying glass for clear sight.
Magnifying lenses are used in Microscopes and Telescopes.
Microscope consists of two convex lenses of different focal lengths.�� The smaller focal length lens is known as objective piece, and the larger focal length lens is known as eye piece. These two lenses are placed inside two metallic tubes blackened from inside, such that they can easily slide into one another. The objective lens is fixed at one end.