Question

Thick plane mirror forms a number of the images of a point source of light. Which image is brightness?
A. First
B. second
C. Third
D. fourth

Answer 1

Hint: When plane mirror is thick the ray will reflect multiple times because of upper surface and below surface but only silvered surface image formed will be brighter.

Complete step by step solution:

$\to $As shown in the figure when thickness is higher in a plane mirror it acts as two surfaces instead of a single surface.
$\to $So it can form multiple images but only one image will be brighter than any other whose fully reflected from the silver surface mirror.
$\to $As we can see in the figure that when the rays are projected on the mirror they get reflected partially by the first surface and form the first image then they go to the silvered mirror and fully reflect from the silvered surface mirror and the second image is formed.
$\to $Hence the second image will be brightest than only other images
$\to $When multiple reflections take place further images are formed due to partial reflections.

Hence, option (B) second is the correct answer.

Additional information:
Types of Mirrors:
Plane Mirror
$\to $These mirrors are flat and these reflect images in their normal proportions, reversed from left to right. This is the most common type of mirror used in houses and hair cutting salons.
Consider Properties of images formed by the plane mirror.
$\to $The image formed by the plane mirror is virtual.
$\to $The image is erect.
$\to $The size of the image is exactly the same as the actual object.

Note:
Distance of the image formed from the mirror is as same as distance of the object from the mirror. Remember when we are solving this type of questions; if the front surface is silvered or the thickness of the mirror is small then only one image will be formed.