Curved Mirrors• Curved mirrors are like plane mirrors • they too have smooth, shiny surfaces that reflect

light. • The surface can either curve in (concave) or out

(convex) as shown below

Concave mirrors

They curve inwards

They can form two types of image

If the light rays come from something close, the

image is upright and magnified

It is a virtual image

If the light rays come from something distant, they

come to a focus after reflection

They converge (come together) to form a small inverted image which can be picked up on a screenThe type of image is called a real imageThe rays of light actually meet to form it.

Converging mirror

Rays from very distant things are nearly parallel to

each other

a concave mirror brings parallel rays to a focus at a

point called the principal focus (F)

the distance from the mirror to the principal focus is

called the focal length

highly curved mirror have short focal lengths

Remember, the concave mirror is part of a sphere

The centre of curvature of a mirror is the centre of the

sphere part of whose surface forms the curved mirror

It is labelled C

The principal axis of the mirror is the line going through the centre of curvature and the centre of the mirror

V

The point on the mirror's surface where the principal axis meets the mirror is known as the vertex and is denoted by the letter V in the diagram . The distance from the vertex to the center of curvature is known as the radius of curvature (represented by R). The radius of curvature is the radius of the sphere from which the mirror was cut. Since the focal point is the midpoint of the line segment adjoining the vertex and the center of curvature, the focal length would be one-half the radius of curvature.

How to locate the image in Converging (Concave) Mirror

To determine the image of an object in front of a concave mirror,

you need to draw at least two incident rays from the top of the object

these rays will be reflected off the mirror and may not cross to form an image

Principal axisC F V

C F V

Drawing an image on Concave mirror

Using three kinds of rays1. The ray parallel to principle axis is reflected

through the focal point (F)

2. The ray passing through F is reflected parallel to the principle axis

3. The ray passing through the center of curvature C is reflected along its same path through C

Three kinds of rays

C F V

Principal axisC F V

Inverted, virtual, smaller

Forming an image (Object beyond C)

Principal axisC F V

Inverted, real, larger

Object between C and F

Principal axis

C F V

Upright, virtual, bigger

Object inside F or between F and V

Principal axisC F V

inverted, real,same size

Object at C

Convex Mirror

Characteristic of convex mirror

1. A convex mirror is part of the outer surface of

a hollow sphere

2. A convex mirror produces diverged rays

3. A convex mirror does not form real images

4. Convex mirror in daily life, used in cars, and

used in stores to observe shoppers.

Principal axis

Principlal axis

V F C

Three kinds of light rays

Principal axis

VF C

Principal axis

Forming an image in a convex mirror

Forming an image in convex mirror

Three kinds of rays1. The ray parallel to the principal axis is reflected as if

it is from focal point (f)2. The ray to focal point is reflected parallel to the

principal axis3. The ray to the center of curvature C is reflected

along its same path through C