Question

A nearsighted student wears contact lenses to correct for a far point that is 4.50m from her eyes. When she is not wearing her contact lenses, her near point is 24cm What is her near point when she is wearing her contacts? Express your answer using two significant figures.

Answer 1

The true far point should be infinity, so we are taking objects from that distance and focusing them at 4.50 m

Apply 1/f = 1/p + 1/q

1/f = 1/-4.5

f = -4.5 m

Now, for the new near point...

1/-4.5 = 1/.24 + 1/q

q = -22.8

Thus the new near point is 22.8 cm