Question

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plzz help me to do this question

Answer 1

The far point of normal human is ∞ but if a person having myopic eye can see only till 80 cm then it means that lens should make image at 80 cm away from it.

→ 1/f = 1/v - 1/u

→ 1/f = 1/(- 80) + 1/∞

→ 1/f = - 1/80 + 0

→ f = - 80

Power = 1/f

• f = - 80 cm or - 0.8 m

→ P = 1/(- 0.8)

→ P = - 1.25

Hence lens used should be concave with power - 1.25.