Turning off the lights is a mirror, and turning on the lights is the nightlight principle.

Turning off the lights is a mirror, and turning on the lights is nightlight's principle and specular reflection. In a darkroom, let the flashlight shine on the mirror on the wall of the darkroom, and the flat mirror will reflect, so the light will be concentrated in one direction. However, the wall is diffuse, and the reflected light shines around, so when the eyes are not in the direction of the reflected light, the light reflected by the mirror does not enter the human eye, and some diffuse light enters the human eye, so the wall is illuminated by diffuse reflection. Due to the specular emission, the mirror is still not bright.