Question

Calculate
the power of eye lens when ciliary muscles are fully relaxed??

Answer 1

A normal eye can see objects from 25cm (near point) till infinity (far point).

So, we take:

Object distance, u = -∞ (- infinity)

Image distance, v = 25 cm

By using lens formula, we get,

1/v - 1/u = 1/f

1/25 - 1/-∞ = 1/f

1/f = 1/25 + 0           [Since, 1/-∞ = 0]

1/f = 1/25

f = 25 cm

For determining the power of the lens, focal length should be in metres.

Therefore, 25/100 = 0.25 m

Power, P = 1/f

P = 1 / 0.25

P = 4 D

Therefore, the power of a normal eye is 4 Dioptres.

Hope this helps u...........