State used of a concave lens.

Explanation

(1) Concave lenses are used for proper working of medical equipment , scanner, CD player- 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 wee can see a large area outside the door.
(3) Concave lenses are used in spectacles to corect nearsightness(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 eyepiece fitted a camera , telescope and microscope -the instruments employing convex lenses.