Understanding the Eye Defect: Hypermetropia
The question asks about an eye defect where a person is unable to see nearby objects clearly. This condition is known as hypermetropia, commonly referred to as farsightedness.
In hypermetropia, the eye's focusing power is insufficient, causing light rays from nearby objects to focus at a point behind the retina, instead of directly on it. This results in blurred vision for close-up tasks.
- Symptoms: Difficulty reading small print, eye strain when doing close work, headaches.
- Cause: Typically occurs when the eyeball is slightly shorter than normal or when the cornea/lens has less curvature than required.
Lens Correction for Hypermetropia
To correct hypermetropia and enable clear focus on nearby objects, a lens is needed that adds converging power to the eye's optical system. This helps redirect the light rays to focus correctly on the retina.
A convex lens is used to correct hypermetropia. Convex lenses are thicker in the middle and converge light rays. By placing a convex lens of the appropriate power in front of the eye, it assists the eye's natural lens in focusing the image of nearby objects sharply onto the retina.
It's important to distinguish this from myopia (nearsightedness), where distant objects appear blurred and the correction involves a concave lens, which diverges light.
Summary of Correction
| Eye Defect Description | Condition Name | Corrective Lens Type |
|---|---|---|
| Cannot see nearby objects distinctly | Hypermetropia | Convex Lens |
| Cannot see distant objects distinctly | Myopia | Concave Lens |
Therefore, the person suffers from hypermetropia and requires a convex lens for correction.
Important Questions from Basic Concepts in Physics
- What happens when the vibration of a sound source becomes faster?
$50 \ \Omega$, $50 \ \Omega$ and $100 \ \Omega$ resistors are connected in series in a circuit. They can be replaced with a single resistor of ______________in the circuit.
- Which of the following statements correctly describes the relationship among the incident ray, the refracted ray, and the normal at the point of incidence when light passes from one transparent medium to another?
- Work done by a force on a body is said to be negative when:
- What is the value of the force exerted by the Earth on a satellite, if the mass of the Earth is $6 \times 10^{24}$ kg and the mass of the satellite is 400 kg. The satellite is orbiting the Earth at a distance of 400 km from its surface. The radius of the Earth is 6400 km and G = $6.67 \times 10^{-11}$ N m$^2$/kg$^2$.
