Lens of power +2.0D is a convex lens

Lens of power +2.0 D is a convex lens.

The radii of curvature of both the sides of a convex lens are 15 cm and if the refractive index of the material of the lens is 1.5, then focal length of lens in air is ......... cm.

When monochromatic red light is used instead of blue light in a convex lens, its focal length will ......

A combination is formed by keeping a convex lens in contact with a concave lens. If both have same focal length of value 25 cm, then power of combination is ...... D.

Graph of position of image vs position of point object from a convex lens is shown. Then, focal length of the lens is

Give scientific reasons for the following statements: To rectify the defect of far-sightedness or hypermetropia, convex lens of suitable focal length is used as corrective lens.

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?

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 ?

A beam of light converges at a point P. Now a lens is placed in the path of the convergent beam 12cm from P. At what point does the beam converge if the lens is (a) a convex lens of focal length 20cm, and (b) a concave lens of focal length 16cm?