A person suffering from myopia cannot see clearly beyond 1 n , What should be the focal length of the concave lens that will correct his vision ?

A person with a myopic eye cannot see objects beyond 1.2 m distinctly. What should be the type of the corrective lens used to restore proper vision ?

A person suffering from far-sightedness or hypermetropia cannot see clearly ......... objects.

A person needs a lens of power - 5.5 dioptres for correcting his distant vision. For correcting his near vision he needs a lens of power +1.5 dioptres. What is the focal length of the lens required for correcting (1) distant vision and (2) near vision ?

The far point of a myopic eye is 100 cm. What is the focal length of the lens required to see very distant (normal far point) objects clearly?

Answer the following questions: (c) Magnifying power of a simple microscope is inversely proportional to the focal length of the lens. What then stops us from using a convex lens of smaller and smaller focal length and achieving greater and greater magnifying power?

An eye camp was organised by the doctors in a village. They found that the eyes of aged people in the village have the near point receded and the far point also gets reduced. Often aged people suffer from both myopia and hypermetropia. Doctors (opthalmologists) provide these people spectacles of bi-focal lenses to correct the defects. The people were happy and grateful to the doctors. Name the eye defect from which the people were suffering

An eye camp was organised by the doctors in a village. They found that the eyes of aged people in the village have the near point receded and the far point also gets reduced. Often aged people suffer from both myopia and hypermetropia. Doctors (opthalmologists) provide these people spectacles of bi-focal lenses to correct the defects. The people were happy and grateful to the doctors. What were benefits to organise such camps in rural areas ? Give two suggestions.

An eye camp was organised by the doctors in a village. They found that the eyes of aged people in the village have the near point receded and the far point also gets reduced. Often aged people suffer from both myopia and hypermetropia. Doctors (opthalmologists) provide these people spectacles of bi-focal lenses to correct the defects. The people were happy and grateful to the doctors. Give any two causes of this defect.

(i) If f =- 0.2 m for a glass lens, what is the power ofthe lens? (ii) The radii ofcurvature ofthe faces of a double convex lens are 15 cm and 12 cm. Its focal length is 15 cm. What is the refractive index of glass ? (iii) Refractive index and radii of curvature oftwo equal plana-convex lens are 1.5 and 20 cm respectively. They are placed in a vessel such that their convex surfaces are in contact at centre and oil ofrefractive index 1.7 is filled in them, then what will be the focal length of combination ?