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A person with myopia can see objects pla...

A person with myopia can see objects plaecd at a distance of 4 m. if he wants to see objects at a distance of 20 m, what should be the focal length and power of the concave lens he must wear?

Text Solution

Verified by Experts

Give that x=4m and y =20m.
Focal length of the correction lens is `f=(xy)/(x-y)`
`f=(4xx20)/(4-20)`
`=(80)/(-16)=-5m`
Power of the correction lens
`=(1)/(f)-=(1)/(5)=-0.2D`
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