Sarthak stands 2 m in front of a long mirror on a wall
Sarthak stands 2 m in front of a long mirror on a wall. He says his image is on the surface of the mirror, so it is 2 m away from him. Fiza says the image appears 2 m behind the mirror, so it is 4 m away from him. Who is right?
Who do you think is right? Pick one.
The answer: Fiza is right, the image appears as far behind the mirror as he is in front of it
Why
Sarthak's idea is natural — the mirror's surface is the only thing actually there, so it feels as if the picture must be painted on it. But a plane mirror's image appears behind the mirror, exactly as far behind it as the object is in front. Light from Sarthak bounces off the mirror and reaches his eyes as if it were coming from a point 2 m behind the glass, so that is where his image appears: 2 m to the mirror plus 2 m behind it makes 4 m from him. That is why a small room with a big wall mirror looks twice as deep. Test: stand in front of a mirror and take one step towards it — your image also takes one step towards the mirror, so the gap between you and your image shrinks by two steps, not one. Fiza is right: the image appears 2 m behind the mirror, so it is 4 m away from Sarthak.
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