Your nearsighted coach cannot focus clearly on objects more distant than 50 cm from his eye.What power lenses are required for him to follow the flight of a batted ball?
A)50
B)-2.0
C)0.67
D)-0.67
E)2.0

Question

Quizplus · Accepted Answer

The power of the lens required can be calculated using the formula:

Power of lens (in diopters) = 1/focal length (in meters)

Here, the coach cannot focus clearly on objects more distant than 50 cm from his eye or 0.5 meters. So, the focal length required to focus on objects at infinity would be:

1/f = 1/0.5
f = 0.5 meters

Now, using the formula above, the power of the lens required can be calculated as:

P = 1/f
P = 1/0.5
P = 2 diopters

However, since the coach is nearsighted, we need to use a concave lens to correct his vision. So, the power of the concave lens required would be the negative of the power calculated above:

P = -2 diopters

Therefore, the best choice is B) -2.0.

Your Nearsighted Coach Cannot Focus Clearly on Objects More Distant