Physics micro-lesson in the second day of junior high school: Why did the disappeared coins reappear?
When the light reflected by the coin is refracted from the water into the air, because the refraction angle is greater than the incident angle, the refracted light is far from the normal relative to the incident light, and the human eye looks against the direction of the refracted light and feels that the light is emitted from the opposite direction of the refracted light, so it feels that the coin reappears.