State used of a concave lens.

Explanation

(1) Concave lenese are used for proper working of medical equipment, scanner, CD plyer-the instruments that employ laser rays.
(2) One or more concave lenses are used in a small safety device, fitted in the peep hole in a door, due to which we can see a large area outside the door.
(3) Concave lenses are used in spectacles to correct nearsightedness (myopia).
(4) A concave lens is used to spread light emitted by the small bulb in a torch over a wide area.
(5) A concave lens is used in front of the eyepiece or inside the eyepiced fitted in a camera, telescope and microscope-the instruments employing convex lenses.