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The spectrum depends upon light of different colours being slowed by different amounts: the refractive index of a given substance, say glass or water, is greater for blue light than for red. You could think of blue light as being a slower swimmer than red, getting tangled up in the undergrowth of atoms in glass or…
Television images are sometimes displayed on giant LED (Light Emitting Diode) hoardings. Instead of a fluorescent screen with an electron beam scanning side to side over it, the LED screen is a large array of tiny glowing lights, independently controllable. The lights are individually brightened or dimmed so that…
The atoms like each other to different degrees. Oxygen, for instance in the air, would like to be next to carbon, and if they get near to each other, they snap together. If they’re not too close though, they repel and they go apart, so they don’t know that they could snap together. It’s just as if you had a ball, it…
If you want to see a rainbow you ' have to have the sun behind you when you look at a rainstorm. Each raindrop is more like a little ball than a prism, and light behaves differently when it Sits a ball from how it behaves when it hits a prism. The difference is that the far side of I raindrop acts as a tiny mirror…
Briefly, a radioactive isotope is a kind of atom which decays into a different kind of atom: for example. one called uranium-238 turns into one called lead-206. Because we know how long this takes to happen, we can think of the isotope as a radioactive clock. Radioactive clocks are rather like the water clocks and…