A plane mirror is a highly polished flat surface with a very high capacity to reflect incident light.
We can understand in a better way how this works with the figure attached:
1. The incident rays coming from the real object reach the mirror and
2.are reflected following the law of Reflection.
3.The prolongation of those reflected rays converge at a point that does not coincide with the actual position of the object. At that point the virtual image of the object is formed.
4.Then, the reflected divergent rays are captured by our eye converging on the retina.
Now, the image is said to be virtual because it is a copy of the object that looks as if the object is behind the mirror and not in front of it or on the surface, but it is not really there. However, it can be seen when we focus it with our eyes.
In addition, the image formed is:
symmetrical, because apparently it is at the same distance from the mirror
the same size as the object.
upright, because it retains the same orientation as the object.
