Question

The optical prescription for a pair of spectacles is Right eye −3.50 D
Left eye −4.00 D
(a) Are these lenses thinner at the middle or at the edges?
(b) Which lens has a greater focal length?
(c) Which is the weaker eye?

Answer 1

Answer:

(a) Yes, these lenses are thinner at the middle because these are concave lenses.

(b) The lens for right eye has greater focal length of -0.28 m

(c) The right eye is the weaker eye.

Answer 2

(a) Yes, these lenses are thinner at the middle .

(b) A greater focal length is on the lens for the right eye.

(c) The weaker eye is  left eye.

Explanation:

The optical recommendation for a pair of glasses is -3.50 D -4.00 D − Right eye

(a) At the middle these lenses are thinner because they're concave lens. Furthermore, the concave lens has negative force.

(b) The lens for the right eye has higher focal length because the power is inversely proportional to the length of the focus.

i.e    $p= \frac{1}{f}$

where p is the power

and f is the focal length.

(c) The left eye is smaller, because it has a reduced focal lens correction.