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Question
A student obtained a sharp image of a burning candle, placed at the farther end of a laboratory table, on a screen using a concave mirror. For getting better value of focal length of the mirror, the subject teacher suggested him for focusing a well illuminated distant object. What should the student do?
(A) He should move the mirror away from the screen.
(B) He should move the mirror slightly towards the screen.
(C) He should move the mirror as well as the screen towards the newly selected object.
(D) He should move only the screen towards the newly selected object.
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Solution
(B)
As the image distance is increased, the object distance would decrease and thus the mirror-screen distance should be decreased. Therefore, the mirror should be moved towards the screen.
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