Question

Name the defect of vision depicted in this diagram stating the part of the eye responsible for this condition.

Answer 1

Step 1: Identify the defect shown in the diagram:
The diagram shows light rays coming from a nearby object and converging at a point behind the retina rather than directly on it.
This condition is called Hypermetropia (farsightedness or long-sightedness).

Step 2: Understand what hypermetropia means:
- A person with hypermetropia can see distant objects clearly.
- However, they have difficulty viewing nearby objects because the image is not focused on the retina.

Step 3: State the part of the eye responsible:
The main reasons for this defect are:
1. Weak lens: The lens is not thick or convex enough to bend (converge) the incoming light rays.
2. Short eyeball: The eyeball is shorter than normal from front to back, which also causes the image to form behind the retina.

Step 4: Conclusion:
The defect of vision shown is Hypermetropia. The part of the eye responsible is the lens, which is too weak, or the eyeball, which is too short. This causes the light rays from nearby objects to focus behind the retina.

Answer 2

Step 1: Understand the defect – Hypermetropia:
Hypermetropia, or farsightedness, is a common defect of vision where a person can see distant objects clearly but finds it difficult to see nearby objects.

Step 2: Cause 1 – Short Eyeball:
- In some individuals, the eyeball is shorter than normal (from front to back).
- As a result, light rays from nearby objects converge to a point behind the retina instead of directly on it.
- This leads to a blurred image of close objects.

Step 3: Cause 2 – Weak Eye Lens:
- Sometimes, the eye lens is not strong enough (not sufficiently convex).
- This means it cannot converge the light rays from near objects effectively.
- Consequently, the image is formed behind the retina, causing difficulty in seeing nearby objects clearly.

Step 4: Conclusion:
Two main causes of hypermetropia are:
1. Short Eyeball: Light focuses behind the retina.
2. Weak Lens: The lens does not converge light rays adequately to focus them on the retina.

Answer 3

Step 1: Identify the defect of vision:
The defect being referred to is hypermetropia (also called farsightedness).
In this condition, a person can see distant objects clearly but has difficulty seeing nearby objects.

Step 2: Understand the cause of hypermetropia:
- This defect occurs when the eyeball is too short or the eye lens has insufficient converging power.
- As a result, light rays from nearby objects focus behind the retina instead of directly on it.

Step 3: Type of lens used for correction:
- A convex lens (also called a converging lens) is used to correct hypermetropia.

Step 4: Role of the convex lens:
- The convex lens converges the incoming light rays before they enter the eye.
- This effectively shortens the focal length so that the image is formed on the retina instead of behind it.
- As a result, the person can see nearby objects clearly.

Step 5: Conclusion:
A convex lens is used to correct hypermetropia. It helps by converging light rays so that they focus on the retina, allowing clear vision of nearby objects.