Core4 mapped NDA questions
Build the idea
Build exam-ready understanding by connecting the core idea, formulas or facts, worked example and previous NDA questions. Focus on why each rule works, then test it under timed conditions.
Concept
The human eye works like a camera: the convex eye-lens focuses light onto the retina, forming a real, inverted image. Common defects are corrected with suitable lenses.
The ability to focus at different distances is called accommodation.
Key Points & Formulas
- Image on retina is real and inverted; the brain interprets it upright.
- Myopia (short sight): corrected with a concave lens.
- Hypermetropia (long sight): corrected with a convex lens.
- Retina contains rods (dim light) and cones (colour).
Worked Example
Q. A person cannot see distant objects clearly. Name the defect and its correction.
Difficulty with distant objects = myopia (short-sightedness).
It is corrected using a concave (diverging) lens.