Question

A person is suffering from myopia, his far distance is 5 m. What is the focal length of his eye lens ?​

Answer 1

Answer:

When the object is at infinity the virtual image should form at 2m

u=∞

v=−2m

f

1

=

v

1

−

u

1

f

1

=

−2

1

−

∞

1

f=−2m

Now power P=

f

1

=

−2

1

=−0.5D

Answer 2

Focal length of his eye lens is -5 m.

Given - Far distance

Find - Focal length

Solution - The formula to be used is -

1/f = 1/v - 1/u

Here, u will he infinity and v will be negative.

Keep the values in formula

1/f = 1/-5

f = -5 m

Hence, focal length of eye lens is -5 m.

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