Chapter 10 Light
  Section How does a mirror reflect light?
    Mirrors that we see every day in bathrooms are very flat surfaces that reflect almost all the light.

The virtual image that seems to be behind the mirror is of the same size of the object from where the rays come from. The distance between the object and the mirror is the same distance between the mirror and the virtual image. The most notable difference is that the virtual image is reversed.

Image and virtual image

   

However, not every mirror is flat. There are also curved mirrors. These mirrors reflect light in special ways.

Let's imagine a soccer ball. Concave mirrors are the ones whose reflecting surface is the inside part of the ball. Convex mirrors are the ones whose reflecting surface is the outside part of the ball.

Now, let's imagine the center of the ball. This is called the center of curvature (C). The line that passes through the center of curvature and the mirror is the principal axis and the midpoint between the center of curvature and the mirror on the principal axis is called the principal focus (F).

In a concave mirror, the reflected ray will pass through the principal focus if the incident ray is parallel to the principal axis. In a convex mirror, the reflected ray will seem to come from the principal focus if the incident ray is parallel to the principal axis.

Concave and convex mirror with ray

These curved mirrors produce an effect enlargement and reduction.

If a box is placed in front of a concave mirror, the virtual image of that box produced by the mirror is larger than the real box. On the other hand, if a box is placed in front of a convex mirror, the virtual image of that box produced by the mirror is smaller than the real box.

Concave and convex mirrors

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