Question

With -6.0 D corrective lenses, Juliana's distant vision is quite sharp. She has a pair of -4.0 D computer glasses that puts her computer screen right at her far point. How far away is her computer?

Answer 1

If Juliana's far point is at infinity with her -6.0 D corrective lenses, then her near point is at:

1/f = 1/do + 1/di

where f is the focal length of the computer glasses, do is the distance of the object (which is infinity), and di is the distance of the image (which is the near point).

Solving for di, we get:

di = 1 / ((1/f) - (1/do))

Since do is infinity, the equation simplifies to:

di = f

So the distance of the image (the near point) is equal to the focal length of the computer glasses.

Since Juliana's computer glasses have a power of -4.0 D, the focal length of the glasses is:

f = 1 / (-4.0 D) = -0.25 m

Therefore, the distance of Juliana's computer screen is 0.25 m or 25 cm away from her computer glasses.

Step-by-step explanation: