Question

A convex lens and a concave lens both are placed side by
side on a printed page. Looking at the image of printing
through the lenses how will you identify the type of lens?

Answer 1

Answer:

Introduction

 Lens: A transparent material bound by two surfaces, of which one or both

surfaces are spherical, forms a lens.

Convex lens: Convex lens is a transparent curved device that is used to refract

light. A lens is usually made from glass. There are two different shapes for lenses.

They are called convex and concave lens. A convex lens is thicker in the middle

and thinner at the edges, it is also called a converging lens. A convex lens will

focus light and make a real and inverted image. The size of the image will depend

on the position of the object and lens.

 Concave lens: A concave lens is thinner in the middle and thicker at the edges. A

concave lens is also called a diverging lens. A concave lens will disperse light and

make an image that is always virtual, upright and smaller than the object.

 Principal axis: The principal axis is a line that is perpendicular to and passes

through the centre of the lens.

 Principal focus: The principal focus, F is the point through which all incident rays

travelling parallel to the principal axis after refraction appear to meet.

 The focal length “ƒ’ is the distance from the center of the lens, O to the principal

focus, F.

 Centre of curvature of lens: A convex lens is made up of two spherical surfaces.

These surfaces are the parts of a sphere. The centre of these spheres are called

centres of curvature of the lens. It is represented by