For example, UV light from the sun is known to cause skin cancer, so what makes it different from the visible spectrum (other than that we can’t see it)? Furthermore, does the spectrum gradually become more harmful, or is it a sudden jump to being harmful?
In: Physics
Light is (sort of) made up of tiny particles called photons. Each photon has a certain amount of energy. The amount of energy depends on (or determines) what type of photon it is. Radio waves are made up of low energy photons. Infrared photons have more energy. Then as we go from red through green to blue light, the energy keeps increasing. Once we get to ultraviolet, the x-ray and finally gamma rays, we have higher and higher energy photons.
Now, the low energy photons are safe. But gradually, the photons begin to be more harmful. A small amount of UV is okay, but too much can be dangerous. A small amount of x-rays or gamma rays can be okay, but it doesn’t take much for it to be bad.
So, why is this the case? Well think of it this way. If you throw a grain of sand at a window, it won’t break. Maybe you throw a whole handful of sand at the window. It’ll still be fine. A bucketful? Probably still okay. This is like a lot of low energy photons. Now, for a high energy photon, let’s say you throw one single brick at a window. It’ll break!
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