An individual is nearsighted his near point is 160 cm and hi

An individual is nearsighted; his near point is 16.0 cm and his far point is 57.0 cm. (a) What lens power is needed to correct his nearsightedness?

(b) When the lenses are in use, what is this person\'s near point?

Solution

Here, for near sight :
P = -100/PR

Where, PR = the far point

So, P = -100/57 = - 1.75 D

(a) So, the lens power needed to correct his nearsightedness = -1.75 D

(b) Again, f = 100/P = 100/-1.75 = -57.14 cm

and, di = -16 cm

So, do = di * f/(di - f)
= (-16 * -57.14)/(-16 - (-57.14)) = (16*57.14) / (41.14) = 22.22 cm
So, the person\'s near point will be 22.22 cm