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Reflection by a Plane Surface

Reflection by a Plane Surface

Reflection takes place from any polished surface, and according to two laws.
1. The angle of reflection- is equal to the angle of incidence.
2nd. The reflected and incident rays are both in the same plane, which is perpendicular to the reflecting surface.

Fig 1

Thus, if A B be the ray incident at B, on the mirror C D, and B E be the ray reflected, the perpendicular P B will divide the angle A B E into two equal parts.
The angle A B P is equal to the angle P B E ; while A B, P B, and E B lie in the same plane.

When reflection takes place from a plane surface, the image is projected backwards to a distance behind the mirror, equal to the distance of the object in front of it, the image being of the same size as the object.

Thus in Fig. 2 the image of the candle c is formed behind the mirror M, at C', a distance behind the mirror equal to the distance of the candle in front of it, an observer's eye placed at E would receive the rays from C as if they came from C'.

Fig 2

The image of the candle so formed by a plane mirror is called a virtual image.