Question

State the range of the power of accommodation of a normal human eye.

Hint:

Normal eye power of accommodation ≈ 4 D.

Answer 1

Range of the Power of Accommodation of a Normal Human Eye

The power of accommodation of the human eye is the ability of the eye lens to adjust its focal length in order to see objects clearly at different distances.

Range of Accommodation:
In a normal human eye, the power of accommodation is approximately 4 dioptres.

Detailed Explanation:

1. The far point of a normal human eye is at infinity.
2. The near point of a normal human eye is about 25 cm.
3. To focus from infinity to 25 cm, the eye lens changes its power by about 4 dioptres.

Power (P) is given by:
P = 1 / f (where f is focal length in metres)

For near point (25 cm = 0.25 m):
P = 1 / 0.25 = 4 D

Conclusion:
The range of power of accommodation of a normal human eye is approximately 4 dioptres, which enables it to see clearly from infinity to about 25 cm.