Optics – Why Plane Mirrors Form Images of the Same Size as Objects

Measurementsopticsreflection

Plane mirror form images of the same size as of the object.

Also if we need to see ourselves completely in mirror, we would require a mirror of at least half out height.

Assume I am 6 feet tall then if I use a mirror 3 feet tall then how come me and my image have that same size, should not my Image by 3 feet tall and if yes then why we say that the Plane mirror form images of the same size as of the object?

Best Answer

The optical ray diagram of a plane mirror may help

plane mirror image

Also here:

rays

Let’s say you have a toy car, and it’s sitting in front of a regular bathroom mirror. The distance between the car and mirror is called the object distance, and it’s always positive. If you look at the image of the toy car in the mirror, it will appear to be the same distance behind the mirror as the real car is in front of the mirror, at the same height. It will also appear to be the same size as the real car. The image of the car looks like it’s behind the mirror (and the light we see does not directly emerge from the image), we say that the image is upright and virtual, and that the image distance is negative.

Because of the geometry of optical rays, plotting them, and measuring the sizes , plane mirror images have the same size as the original.

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