Photon, also called light quantum, is a tiny packet of electromagnetic energy. It moves at an amazing speed of 300,000 kilometers per second, It has no mass, and loses no energy! When photons hit a surface, they would scatter, and this scattering of photons from the surface of an object is what enables our eyes to see it. So when you switch on the light. You know what happens. But have you ever asked yourself what happens to the photons when we switch off the light? Do they completely disappear instantly? Well, when you switch off the light, there are still photons in the room. If you use an infrared camera you’ll be able to see them for some time. However, these photons are scattered countless times until they are entirely absorbed by surfaces and become inactive; That’s the reason, you can’t see them. But as mentioned before those photons move so fast. Because of that it feels like they disappear pretty much instantly. On the other hand, when light is on, trillions of new photons are emitted, which fly in all directions. They hit any object present in their path, which absorbs most of those photons, but also reflect off a small fraction of it that helps us see the stuff around us. I hope now you got the answer. That’s it for this article. Thank you so much for reading.