Question

A man having myopia, cannot see clearly an object kept beyond 75 cm. What kind of
lens is necessary if he wants to see the distant object ? Also, find focal length of the
lens.

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Answer 1

Answer:

Nature of the lens -> Concave lens

• u=
• $\infty$
• v= - 75 cm
• $\frac{1}{v} - \frac{1}{u} = \frac{1}{f}$
• f = - 75 cm = - 0.75 m

Power = 1/f = 1/ - 0.75 = - 1.33 D