A myopic eye is not able to see distinctly the objects placed beyond 2 m from it. Determine the nature, the focal length and the power of lens used to correct the defect.

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Solution

When a person is suffering from myopia, a concave lens is used to cure the defect.
Here distance of far point x $=$ 2m
So the focal length of the concave mirror f $=$ $-$ x $=$ $-$ 2
Power of the lens $=$ 1 $/$ f $=$ 1 $/$ ( $-$ 2) $=$ $-$ 0 $\cdot$ 5 D

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(ii) the type of the corrective lens used to restore proper vision and how this is correct by the use of this lens.

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A myopic eye is not able to see distinctly the objects placed beyond 2 m from it. Determine the nature, the focal length and the power of lens used to correct the defect.

When a person is suffering from myopia, a concave lens is used to cure the defect. Here distance of far point x= 2m ​So the focal length of the concave mirror f = -x = -2 Power of the lens = 1/f = 1/(-2) = -0·5 D

When a person is suffering from myopia, a concave lens is used to cure the defect.
Here distance of far point x $=$ 2m
So the focal length of the concave mirror f $=$ $-$ x $=$ $-$ 2
Power of the lens $=$ 1 $/$ f $=$ 1 $/$ ( $-$ 2) $=$ $-$ 0 $\cdot$ 5 D