The most important laws of reflection that you must be aware of are:
When a ray of light falls on a mirror, it is sent back to the first medium in a certain direction according to certain laws.
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(i) The incident ray, the reflected ray and normal at a point lie in the same plane.
(ii) The angle of incidence is equal to the angle of reflection; the angles being measured between the normal and the respective rays.
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When a surface is rough, the rays of a beam of light falling on it are not regularly reflected in one direction, but are irregularly reflected or scattered in all directions, and hence the surface becomes visible from all parts of the room.
Illustrations:
(i) When an object is placed between two mirrors parallel to each other we see a number of images due to successive reflections. They look smaller because their distance from the eye is successively increased.
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(ii) Construction of a toy, called kaleidoscope, is due to successive reflection at the surface of inclined mirrors.
(iii) When a candle is placed close in front of a thick glass mirror and we look somewhat obliquely at the mirror, a number of images are seen due to multiple reflections. Of these the images nearest the candle will be brightest of the series. The other images formed gradually decrease in brightness.
The first image is formed by the light which is reflected from the front surface of the mirror. Most of the incident light penetrates the glass. On reaching the silvered surface at the back, it is all reflected to the front surface, where some of it is reflected back to the silvered surface and is again reflected to the front surface and so on. Each time some light comes out showing one image.