Definition of the plane mirror
A plane mirror is a mirror that has a flat surface, where one of its surfaces is coated with reflective metal so that the surface of the plane mirror can reflect more than 95 percent of the light that strikes it. If you shine a flashlight toward a plane mirror surface, the plane mirror reflects the light so that your eyes glare if the mirror reflects the flashlight to your eyes. Conversely, if you stand in front of a mirror surface during the day, your face reflects sunlight toward the surface of the mirror, and at the same time, the mirror reflects light back toward you. If you stand in front of a plane mirror surface at night, then your face reflects the light of the electric light
towards the plane mirror surface, and at the same time, the plane mirror reflects the light of the electric light back towards you.