Distinguish between:

Concave lens and Convex Lens

Explain the working of an astronomical telescope using refraction of light.

Distinguish between:

Farsightedness and Nearsightedness

What are the function of iris and the muscles connected to the lens in the human eye?

Solve the following examples.

The doctor has prescribed a lens having power +1.5 D. What will be the focal length of the lens? What is the type of the lens and what must be the defect of vision?