An optometrist has perscribed you 2D glasses. This means
a) you are farsighted and the focal lenght of your glasses lens is +.5m
b)you are nearsighted and the focal lenght of your glasses lens is +.5m
c)you are farsighted and the focal lenght of your glasses lens is -.5m
d)you are nearsighted and the focal lenght of your glasses lens is -.5m
I am really confused with this question But i think it's a).
To determine the correct answer, we need to understand the difference between farsightedness and nearsightedness, as well as the basic principles of lens prescriptions.
Farsightedness (hyperopia) is a common vision condition in which distant objects may appear clear, but close objects appear blurry. This occurs when the eyeball is shorter than normal or when the cornea (front surface of the eye) is too flat. Farsighted individuals have difficulty seeing objects up close.
Nearsightedness (myopia), on the other hand, is a vision condition in which distant objects appear blurry, while close objects are seen clearly. It happens when the eyeball is longer than normal or when the cornea is too steeply curved. Nearsighted individuals have difficulty seeing objects at a distance.
Now let's focus on the details of the lens prescription. A lens prescription is typically written in diopters (D), which is a unit of measurement representing the optical power of the lens. A positive diopter value (+) indicates farsightedness (convex lens), and a negative value (-) indicates nearsightedness (concave lens). The higher the diopter value, the stronger the lens power.
In this case, the prescription states that you have been prescribed 2D glasses. Since the lens prescription is not mentioned as negative or positive, we need to determine if you are farsighted or nearsighted based on the given information.
If the focal length of the glasses lens is +0.5m, this would mean that you are farsighted. A positive focal length is associated with a convex lens, which is used to correct farsightedness. Hence, your assumption that option "a)" is the correct answer appears to be correct.
Therefore, the answer to this question is: a) you are farsighted, and the focal length of your glasses lens is +0.5m.