(a) Define the term power of accommodation of human eye. Write the name of the part of eye which plays a major role in the process of accommodation and explain what happens when human eye focuses (i) nearby objects and (ii) distant objects.
OR
(b) Draw a ray diagram to show the formation of a rainbow in the sky. On this diagram mark A – where dispersion of light occurs, B – where internal reflection of light occurs and C – where refraction of light occurs. List two necessary conditions to observe a rainbow.

Question

Tara's grandmother is 70 years old and has a passion for embroidery. She faces difficulty in threading the needle as the eye of the needle appears blurred. The ophthalmologist diagnosed it as an age-related disorder.

(a) Name the eye disorder she is suffering from.
(b) How can the above defect be corrected?
(c) Where is the image formed in the above disorder?

Answer 1

(a) Power of Accommodation: The human eye's capacity to adjust lens focal length for objects at different distances.
• Eye Component Involved: Ciliary muscles are crucial for accommodation.
• Focusing Mechanism:
– (i) Near Objects: Ciliary muscles contract, increasing lens convexity (thickness) and refractive power for near focus.
– (ii) Distant Objects: Ciliary muscles relax, decreasing lens convexity (thickness) and refractive power for distant focus.

(b).
Ray diagram
Rainbow Observation Requirements:
• The observer must have the Sun behind them.
• Airborne water droplets are needed to refract, disperse, and reflect sunlight.

Solution and Explanation

Top Questions on The Human Eye

Questions Asked in CBSE Class X exam