1.

A person is using a concave lens of power -1.5D for distant vision. How has far point of her eye shifted ??

Answer»

Answer:

Unknown.

Explanation:

P = 1/F

Given : P = - 1.5 D

→ - 1.5 D = 1/f

→ f = 1/(- 1.5)

→ f = - 2/3 or - 0.67 m

Or in other units, focal length

→ - 0.67 × 100 = - 67 cm

Mirror Formula

1/f = 1/v - 1/u

→ 1/(- 67) = 1/v - 1/u

Since the question doesn't mention where the object has placed hence VALUE of v will be in terms of u

→ - 1/67 + 1/u = 1/v

→ (67 - u)/67u = 1/v

v = 67u/(67 - u)

Hence far point is surely SHIFTED from ∞.



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