Friday is here again, and with it the weekly "A Taste of Physics" column — issue #8
This time: ions, plasma, and microwave energy
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The cup in the photo is sitting inside a microwave. It's made of quartz, and inside it is a piece of magnesium.
The microwaves cause the magnesium to release electrons and turn into plasma, producing a spectacular display of blue lightning.
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And for the curious — here is the full scientific explanation behind the process:
The cup is made of quartz to withstand the high temperatures involved, and also because quartz allows microwaves to pass through it and reach the magnesium inside.
Magnesium atoms consist of a nucleus surrounded by electrons arranged in 3 shells.
The electrons in the outermost shell are relatively easy to strip from the atom by adding energy to their orbital motion.
The microwaves add energy to the magnesium atoms, causing electrons to break free and move about freely.
The magnesium atoms become positive ions — atoms carrying a positive electric charge (due to the loss of a negatively charged electron).
The mixture of ions and electrons is called plasma.
As the plasma cools, the electrons recombine with the positive ions, re-forming stable atoms.
In this process, energy is released in the form of light — and that light is precisely the lightning bolts that appear in the experiment.
#taste_of_physics #plasma #magnesium