Question

A man is 6 ft tall. What is the smallest size plane mirror he can use to see his full image ?
a) 3ft b)6 ft c) 12ft d)24 ft

Answer 1

Answer:

3 ft

Explanation:

Hence the minimum length of the mirror required to see the entire image of a man of height of 6 feet is 3 feet. So, the correct answer is “Option C”. Note: The mirror should be placed at the top i.e. at the line of sight of the man, of half its length to see the entire image.

Answer 2

a) 3ft

We know that by the principle of reflection, the angle of incidence(i) is equal to the angle of reflection(r).

So if the ray of light travels from the bottom to the top of the person then only he will be able to see his clear image.

That means the ray emitting from the foot of the person will strike the mirror and then after reflection of that ray, it will reach the eye of the person.

For this, we can say that the minimum height of the plane mirror that is required to enable the person to see his full image in the mirror is half of the height pf the person

Hence the smallest size of the plane mirror he can use to see his full image will be 3ft (6/2).