Optics

Curved Mirror

Real or Virtual

1. A real image is formed by the intersection of light rays from a pint of the object.

2. The term ‘virtual” is chosen to distinguish this type of image from a “real” image, in which the rays do not pass through a point of intersection

The image is always inverted and can be projected on a screen.

Object behind C

FC

Image: Between C and F

Nature: Inverted, diminished, real.

(5) Object between F and the mirror

Image: Behind the mirror

Nature: Erect, magnified, virtual.

FC

Try yourself !

Convex Mirror

F C

Image: Behind the mirror

Nature: Erect, diminished, virtual.

Reversibility of light

(1) Object behind C

FC

FC

(3) Object between C and F

Try yourself !

1. A student uses a concave mirror to form a sharp image of an illuminated object ‘P’ on a screen as shown in the diagram below.

The distance between the object and the mirror is found to be 0.5m(a) What is the focal length of the mirror?(b) Explain your answer with the aid of a ray diagram.

3. The letter “F” is put in front of a concave mirror and the image is formed on a translucent screen.a. Looking at the screen from A, the image seen is _______.b. Looking at the screen from B, the image seen is _______.c. Looking into the mirror from B, the image seen is ______.

2 The diagram below shows an experiment used to find the focal length of a concave mirror. 

 

a. Describe briefly how the experiment is performed?b. Draw a ray diagram showing how an image is formed in the above experiment.c. If the distance between the mirror and the screen is 10cm, what is the focal length of the mirror?

Application of Curved Mirror

1. Convex Mirror

2. Concave Mirror

Convex Mirror

The image formed by a convex mirror is always :

1. erect

2. diminished

3. virtual

Convex Mirror

F C

Image: Behind the mirror

Nature: Erect, diminished, virtual.

Convex Mirror

1. used in supermarkets to protect against shoplifters.

Convex Mirror

2. used to help drivers see a wider view at corners

Concave Mirror

The image formed by a convex mirror may be:

1. Erect & Magnified & VirtualOr

2. Inverted & real (magnified / diminished)

Object between F and the mirror

Image: Behind the mirror

Nature: Erect, magnified, virtual.

FC

Try yourself !

Concave Mirror

1. make-up mirrors as they give a magnified image.

Image of the face is magnified

Concave MirrorsConcave Mirrors

2. Reflecting Telescope

the dim light from a distant star can be collected and concentrated at the focus.

Distance Object

F

Image: At focus

C

Parallel beam

Try yourself !

Concave MirrorsConcave Mirrors

Object at F

F

Image: At infinity

C

Parallel beam

Try yourself !

3. use as torches, car head lights

Concave MirrorsConcave Mirrors

Concave MirrorsConcave Mirrors

3. Reflectors