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प्रश्न
When an object of height 1 cm is kept at a distance 4 cm from a concave mirror, its erect image of height 1.5 cm is formed at a distance 6 cm behind the mirror. Find the focal length of mirror, by drawing.
उत्तर
A ray passing parallel to the principal axis passes through the focal point after reflection. Hence, the focal length is 12 cm.
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