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Question
Define the terms focus and focal length of a concave mirror. Draw diagram to illustrate your answer.
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Solution
Focus of a concave mirror: The focus of a concave mirror is a point on the principal axis through which the light rays incident parallel to principal axis, pass after reflection from the mirror.
Focal length of a concave mirror: The distance of the focus from the pole of the concave mirror is called its focal length.
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Explain the following term related to spherical lenses:- aperture
Name the spherical mirror which can produce a real and diminished image of an object.
Write true or false
A virtual image formed by a spherical mirror is always erect and situated behind the mirror.
A student obtained on a screen the sharp image of a candle flame placed at the farther end of laboratory table using a concave mirror. For getting better value of focal length of the mirror, the teacher suggested to him to focus the sun. What should the student do?
(A) Should move the mirror away from the screen.
(B) Should move the mirror towards the screen.
(C) Should move the mirror and screen both towards the sun.
(D) Should move only the screen towards the sun.
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