Question

Ankit from standard 10 use spectacle the power of the lens in his spectacles is - 0.5 D answer the following question state the type of lens used in the spectacle be name the defect of vision Aniket is suffering from c find the focal length of the lens used in the spectacles

Answer 1

The type of lens used in spectacle is concave lens.

The name of defect of vision is myopia or near sightedness.

As we know the power is the reciprocal of focal length, therefore, power of lens = 10/5 = 2 cm.

Answer 2

The type of lens used in the spectacle is Concave lens.

The defect of vision with which Aniket is suffering from is Myopia i.e. he cannot see the objects that are closer to him.

The focal length of the lends used in the spectacles is calculated using the following formula:

Power of lens = 1/focal length

Focal length =1/ power of lens

In the question, the power of lens is given as 0.5 D

Focal Length = 1/0.5 = 2