Question

Sunita from Std. X uses spectacles. Her
spectacles number is -1.5D. Answer the
following questions:
a) Name the defect of eye from which she
is suffering.
b) What type oflens is she using ?
c) Find the focal length of the lens.​

Answer 1

Explanation:

a)presbiopia

b)concave

Answer 2

Answers are as follows -

a) Since the lens used by Sunita has negative power and hence negative focal length, she is suffering from myopia or near sightedness.

b) Sunita is using concave lens in spectacles to correct her vision.

c) Focal length of lens = 1/P, where p is power.

Focal length = -1/1.5

Focal length = -0.67 metre.

Hence, focal length of lens is -0.67 metre.