Fill ups
Hypermetropia is corrected by ………….lens.

In these question, a statement of asertion followed by a statement of reason is given .Choose the correct answer out of the following choices: Assertion and reason both are correct statements and reason is correct explanation for assertion. Assertion and reason both are correct statements but reason is not correct explanation for assertion. Assertion is correct statement but reason is wrong statement. Assertion is wrong statement but reason is correct statement. Assertion:If a convex lens is kept in water,its convergent power decreses. Reason:Focal length of convex lens in water increases.

In these question, a statement of asertion followed by a statement of reason is given .Choose the correct answer out of the following choices: Assertion and reason both are correct statements and reason is correct explanation for assertion. Assertion and reason both are correct statements but reason is not correct explanation for assertion. Assertion is correct statement but reason is wrong statement. Assertion is wrong statement but reason is correct statement. Assertion:The resolving power of a telescope is more ,if the diameter of the objective lens is more. Reason:Objectives lens of large diameter collects more light.

In these question, a statement of asertion followed by a statement of reason is given .Choose the correct answer out of the following choices: Assertion and reason both are correct statements and reason is correct explanation for assertion. Assertion and reason both are correct statements but reason is not correct explanation for assertion. Assertion is correct statement but reason is wrong statement. Assertion is wrong statement but reason is correct statement. Assertion:Position of image approches focus of a lens,only when object approaches infinity. Reason:Paraxial rays inident parallel to principal axis intersect at the focus after refraction from the lens.

Define optical centre of a lens.

A doctor has prescribed a corrective lens of power+ 1.5 D.Find the focal length of lens.Is prescribed lens diverging or converging?

What is a lens maker's formula? Why is it called so? Derive it for a thin convex lens.