The incident ray, the reflected ray and the normalline all line in the same plane.

PLANE MIRROR

Ray of incidence

Ray of reflection

Normal line

The incident ray or ray of incidence refers to thelight ray that is directed towards the plane mirror.

PLANE MIRROR

Ray of incidence

The normal line refers to an imaginary line that isperpendicular to the plane mirror.

PLANE MIRROR

Normal line

The reflection ray or ray of reflection refers to theray that is directed away from the plane mirror.

PLANE MIRROR

Ray of reflection

PLANE MIRROR

Angle of incidence = angle of reflection

i° = r°

i° r°

PLANE MIRROR

The angle of incident (i°) is the angle between thenormal line and the ray of incidence.

i°

PLANE MIRROR

r°

The angle of reflection (r°) is the angle between the normal line and the ray of reflection.

Smooth surfaces like the calm waterallows light to be reflected evenly.

This is known as a specular reflection.

Rough surfaces like the rippled and paddledwater allows light to be reflected unevenly.

This is known as a diffuse reflection.

The figure shows a light ray striking a surface of a plane mirror at an angle of 50°.

50°

(a) Determine the angle ofincidence.

(b) Complete the ray ofreflection.

The figure shows a light ray striking a surface of a plane mirror at an angle of 50°.

50°

(a) Determine the angle ofincidence.

ANSWERThe angle of incidence is betweenthe ray of incidence and thenormal line.

The normal line is perpendicularto the plane mirror.

90° – 50° = 40°

40°

Normal line

The figure shows a light ray striking a surface of a plane mirror at an angle of 50°.

50°

(b) Draw the ray of reflection.

40° 40°

ANSWERi = 40°

i = r = 40°

Ray of reflection is drawn awayfrom the normal.

Complete the diagram by sketching reflected rays for an uneven surface.

Complete the diagram by sketching reflected rays for an uneven surface.

ANSWERThe reflected rays of the incident rays are drawn randomly but the ray isstill a straight line.

Real Object

Virtual Image

Rays of light do not meetto produce the image.

3. Upright (normal way up).

1. Same size as the object.

2. Virtual.

4. Appears located farinside the mirror asobjects are in front.

5. Lateral inversion(reverses left andright).