Question

Question 13
The focal length of the eye lens increases when eye muscles

(a) are relaxed and lens becomes thinner
(b) contract and lens becomes thicker
(c) are relaxed and lens becomes thicker
(d) contract and lens becomes thinner

Answer 1

Option (a) is correct.
When the eye is relaxed and the interior lens is the least rounded, the lens has its maximum focal length for distant vision. As the muscle tension around the ring of muscle is increased and the supporting fibers are thereby loosened, the interior lens rounds out to its minimum focal length. Thus, the focal length of the eye lens increases when eye muscles relaxed and becomes thinner.