A convex lens of focal length `30 cm` and a concave lens of focal length `60 cm` are placed in combination. If an object is placed `40 cm` away from the combination, find the position of the image.
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Here, `f_(1) = 30cm, f_(2) = -60 cm` `u = - 40 cm, v = ?` `(1)/(F) = (1)/(f_(1)) + (1)/(f_(2)) = (1)/(30) - (1)/(60) = (1)/(60)` From `(-1)/(u) + (1)/(v) = (1)/(F)` `(1)/(v) = (1)/(F) + (1)/(u) = (1)/(60) - (1)/(40) = (-1)/(120)` `v = -120 cm` which is the position of the image.
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