Question

With -5.5 D corrective lenses, Juliana's distant vision is quite sharp. She has a pair of -3.5 D computer glasses that puts her computer screen right at her far point. How far away is her computer? sfar=?

Answer 1

Juliana's -3.5 D computer glasses indicate her far point is at -0.2857 meters, or 28.57 cm, which is the optimal distance at which she should place her computer for clear vision.

Step-by-step explanation:

Juliana uses -3.5 D computer glasses for her vision correction. Diopter (D) is the unit of measurement for the optical power of a lens, which is the inverse of the focal length in meters. Based on the given diopter value for her glasses, we can calculate her far point, which is the furthest distance at which she can see objects clearly without additional correction. The formula to find the far point (sfar) is given by sfar = 1/D when D is in diopters and sfar is in meters. Therefore, for a -3.5 D lens:

sfar = 1/(-3.5 D) = -0.2857 meters

Since a negative sign indicates a virtual image in optics, we interpret this as Juliana being able to see clearly up to 28.57 cm from her eyes. Thus, her computer should be positioned approximately 28.57 cm away for optimal clarity.