A boy with a mouth 3 cm wide stands 4 m away from a plane mirror. Where is his image and how wide is the image of his mouth?

Question

Question

This question was previously asked in

RRB JE 29 May 2019 (Shift 2) CBT 1 Official Paper

Answer 1

The correct answer is Option 1

Key Points

8 m away from him and mouth image is 3 cm wide is the correct answer.
In a plane mirror, the image is formed at the same distance behind the mirror as the object is in front of it.
If the boy stands 4 m away from the mirror, his image will appear to be 4 m behind the mirror.
Therefore, the total distance between the boy and his image will be 4 m (in front) + 4 m (behind) = 8 m.
The width of the image remains the same as the width of the object in a plane mirror, hence the width of the mouth image is 3 cm.

Additional Information

Plane mirrors create virtual images that are upright and of the same size as the object.
The distance of the image behind the mirror is equal to the distance of the object in front of the mirror.
The virtual image cannot be projected on a screen since it appears to be behind the mirror.
The law of reflection states that the angle of incidence is equal to the angle of reflection, which is why the image distance is the same as the object distance.