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InterviewSolution
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a List four characteristics of the image formed by a concave lens offocal length 20 em when the objeet is placed at a distance of 40 cmplacedatafrom its optical centre. , sanooptb) The size ofimage of an objeet by a convex lens of focal length 20 cmie observed to be reduced to E rd of its size. Find the distance of theobject from the optical cemtre of the lens. |
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Answer» CONCAVE MIRRORS;1. They always produce real and inverted images except when an object is placed between the mirror pole and the focus which gives erect virtual images. (for real objects)2. They produce magnified, diminished and same size images. 3.A parallel beam of incident light is concentrated on its focus and thus such a mirror is called a convergent mirror. Also a light source placed at the focus produces a parallel light beam.4.Sign convention: The focal length and radius of curvature are taken as negative.If focal length is at 20cm then radius of curvature is 2f=40cmhencethe image is at centre of curvaturehence the image formed will be real inverted at centre of curvature and of the same size |
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