Spherical Mirror class 10

Last updated on May 19th, 2023 at 09:26 pm

In this post, we will find out what Spherical Mirror is. We will define a spherical mirror, list down the uses of this type of mirror, and discuss its sign convention. We have already one dedicated post covering ray diagrams of different types of images formed by the spherical mirror, which you should check. In this post, we will also cover different important terms related to Spherical Mirrors, and image formation by spherical mirrors. This post is quite useful as class 10 spherical mirror notes.

What is spherical mirror | spherical mirror definition

A mirror having a curved reflecting surface is called a spherical mirror. A spherical mirror is part of a sphere.

Types of Spherical Mirror – concave and convex mirrors

There are 2 types of Spherical Mirrors. These are [a] Concave mirrors and [b] Convex mirrors.

Concave Mirror is a Spherical mirror with a reflecting surface curved inwards.

Convex Mirror is a Spherical mirror with a reflecting surface curved outwards.

Uses of a spherical mirror

To discuss the uses of spherical mirrors, we will take the uses of convex spherical mirrors and concave spherical mirrors separately.

Uses of Concave Mirror

• Used in torches, searchlights, and headlights of vehicles.
• Used to see a large image of a face as a shaving mirror
• Used by dentists to see large images of the teeth
• The large concave mirror is used to focus sunlight (heat) in solar furnaces.

Uses of Convex Mirror

• Used as a rear-view mirror in vehicles because it gives an erect image.
• It also helps the driver to view large areas.

Sign convention for reflection by spherical mirror | sign convention for spherical mirror

Sign Convention for Reflection by Spherical Mirror

1. The object is always placed on the left side of the mirror.

2. All distance should be measured from pole (P), parallel to the principal axis.

3. Take ‘P’ as the origin. Distances measured Right of the origin (+x- Axis) are taken as positive and Distances measured Left of the origin (-x-Axis) are taken as negative.

4. Perpendicular to and above the principal axis (+y-Axis) is taken as positive. Perpendicular to and below the principal axis (-y-Axis) are taken as negative.

Terms related to the spherical mirror

Pole: The center of the reflecting surface of a spherical mirror is known as Pole. Pole lies on the surface of the spherical mirror. The Pole is generally represented by ‘P’.

Centre of Curvature: The center of the sphere; of which the reflecting surface of a spherical mirror is a part; is called the center of curvature of the spherical mirror. The Centre of curvature is not part of a spherical mirror rather it lies outside the mirror. The Centre of curvature is denoted by the letter ‘C’.

Radius of Curvature: The radius of the sphere; of which the reflecting surface of a spherical mirror is a part, is called the Radius of Curvature of the spherical mirror. The radius of curvature of a spherical mirror is denoted by the letter ‘R’.

Principal Axis: Imaginary line passing through the center of curvature and pole of a spherical mirror is called the Principal Axis.

Focus or Principal Focus: The point on the principal axis at which parallel rays, coming from infinity, converges after reflection is called the Focus or Principal Focus of the spherical mirror. Focus is represented by the letter ‘F’.

Image formation by Spherical Mirror

Let’s see how image formation happens for 2 types of spherical mirrors.

Image formed by a convex spherical mirror – for different object positions

There are only two possibilities for the position of an object in the case of a convex mirror, i.e. object at infinity or an object between infinity and the pole of a convex mirror.

Read our post on ray diagrams of different types of images formed by the convex spherical mirror

Image formed by a concave spherical mirror – for different object positions

The formation of the image depends upon the position of the object.
There are six possibilities for the position of the object in the case of the concave mirror.

Read our post on ray diagrams of different types of images formed by the concave spherical mirror

Spherical Mirror – FAQ