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A person who can see things most clearly...

A person who can see things most clearly at a distance of `10 cm`. Requires spectacles to enable to him to see clearly things at a distance of `30 cm.` What should be the focal length of the spectacles ?

A

15 cm (Concave)

B

15 cm (Convex)

C

10 cm

D

0

Text Solution

Verified by Experts

The correct Answer is:
A
u = - 30 cm , u = - 10 cm
`(1)/(f) = (1)/(v) - (1)/(u) = (1)/(-10) + (1)/(30) =- (1)/(15) = -15 ` cm .
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