When an object is placed at a distance of 50 cm from a concave spherical mirror, the magnification produced is - 1 2 . Where should the object be placed to get a magnification of - 1 5 ?

Given: Object distance, u = - 50 cm Magnification, m = − 1 2 Let the image distance is v and the focal length is f . The magnification, m = − v u That is, − 1 2 = − v u or v = u 2 = − 25 cm Now, using the mirror formula, we can write, 1 f = 1 u + 1 v . That is, 1 f = 1 − 50 + 1 − 25 = 3 − 50 or f = − 50 3 cm Now to obtain magnification of − 1 5 , m = − v u − 1 5 = − v u or v = u 5 Now, using the mirror formula, we can write 1 f = 1 u + 1 v That is, 3 − 50 = 1 u + 5 u = 6 u or u = - 100 cm To obtain magnification of - 1 5 , the object should be placed at distance 100 cm from the concave spherical mirror.

E M B I B E

Science for Tenth Class Part - 1 Physics>Chapter 4 - Reflection of Light>Short Answer Type Questions>Q 20

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When an object is placed $20 cm$ from a concave mirror, a real image magnified three times is formed. Find where must the object be placed to give a virtual image three times the height of the object?

Important Questions on Reflection of Light

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10th CBSE

IMPORTANT

Science for Tenth Class Part - 1 Physics>Chapter 4 - Reflection of Light>Short Answer Type Questions>Q 21

A dentist’s mirror has a radius of curvature of $3 cm$ . How far must it be placed from a small dental cavity to give a virtual image of the cavity that is magnified five times?