1. What does the negative power indicate?
2. What does the positive power indicate?
3. Generally which type of spectacles do most of the
students use?
4. What defect of eyesight do most of the students suffer
from?
5. Give two possible reasons for the above defect.
Answer:
(1) The negative
power indicates that the spectacles used by the students have concave lens.
(2) The positive
power indicates that the spectacles used by the students have convex lens.
(3) Diverging or
concave lens spectacles are generally used by the students.
(4) Most of the
students suffer from the eye defect known as myopia (near sightedness).
(5) The two possible
reasons for the eye defect (myopia) are
1. Converging power of the eye lens becomes high
as ciliary muscles do not relax sufficiently.
2. Length of the eye ball increases as the
distance between the eye lens and the retina increases.
