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The least distance of vision of a longsi...

The least distance of vision of a longsighted person is 60 cm. By using a spectacle lens, this distance is reduced to 12 cm. The power of the lens is

A

`+5.0 D`

B

`+(20/3) D`

C

`–(10/3) D`

D

`+2.0 D`

Text Solution

Verified by Experts

The correct Answer is:
B
`v = - 60 cm, u - 12 cm `
`(1)/(f) = (1)/(v) - (1)/(u)`
` rArr - (1)/(60) + (1)/(12) = (1)/(f) rArr f = 15 ` cm
`P = (100)/(f(cm)) = (100)/(15) = (20)/(3) `D.
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