Question

Usually Doctors, after testing for defects of vision, prescribe the corrective lens indicating their

• A. radius of curvature
• B. refractive index
• C. mass
• D. power

Answer 1

The Correct Option is D

When doctors test for defects of vision such as myopia (short-sightedness) or hypermetropia (long-sightedness), they prescribe corrective lenses based on their power.

The power of a lens is a measure of its ability to converge or diverge light rays and is given by the formula:

\[ P = \frac{100}{f} \]

Where:

• \( P \) is the power in diopters (D)
• \( f \) is the focal length in centimeters

Doctors write prescriptions using the unit diopter (D), which directly corresponds to the power of the lens required to correct the vision.

Final Answer: power

Answer 2

To determine what doctors typically indicate when prescribing corrective lenses, let us examine each option:

• Radius of curvature: This refers to the physical radius of the lens surface and affects the lens's focusing power. However, it is not usually specified in prescriptions to patients.
• Refractive index: This is a measure of how much a material bends light. While it is important in lens manufacturing, it is not specified in prescriptions.
• Mass: The mass of the lens is related to its weight and feel but plays no role in the lens's corrective function, thus not included in prescriptions.
• Power: This is the most relevant metric and is a measure of the lens's ability to converge or diverge light, expressed in diopters (D). The power required corrects specific defects of vision, such as myopia (nearsightedness) or hyperopia (farsightedness).

Therefore, doctors prescribe lenses by indicating their power, as it directly affects how the lens will correct the vision. Power is calculated based on the specific defect and visual acuity required.