When an illuminated object is held in front of a thick plane glass mirror, several images are seen, out of which the second image is brightest. Give reason.

When an object is observed through a thick mirror, silvered at its back, a large number of images are obtained. Out of all the images, the second image is the brightest. In this case, the first image is formed by reflection at the first surface, which is the unsilvered surface of the mirror. The second image is formed after reflection from the rear silvered surface, which sends the maximum amount of light. Rest of the images formed are due to internal multiple reflections which occur inside the mirror. These images contain a lesser amount of light and so their intensity gradually decreases.