31. A person can't see objects beyond 25 cm. The power of the lens to correct vision will be (a) -4 D (b) -2 D (c) - 1D (d) +2D
Share
31. A person can't see objects beyond 25 cm. The power of the lens to correct vision will be (a) -4 D (b) -2 D (c) - 1D (d) +2D
Sign Up to our social questions and Answers Engine to ask questions, answer people’s questions, and connect with other people.
Login to our social questions & Answers Engine to ask questions answer people’s questions & connect with other people.
Explanation:
The power of a lens is calculated using the formula:
Power (P) = 1 / F
Where F is the focal length of the lens in meters.
If a person can't see objects beyond 25 cm, this means their far point is 25 cm. To find the focal length, you can use the formula:
Focal Length (F) = 1 / Far Point
F = 1 / (25 cm) = 1 / (0.25 m) = 4 meters
Now, you can calculate the power:
P = 1 / F = 1 / 4 = 0.25 Diopters
Since the power is positive, the correct answer is:
(d) +2D ..