Microwave Physics

Often, hot cocoa is made by heating either milk or water in a microwave oven. This is because it's quick and heat up the liquid fairly well. But how does a microwave actually work? We all have them in our homes and we use them all the time, but what actually is the physics behind microwave ovens?

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The inside of a microwave oven actually acts as a Faraday cage, keeping the microwave radiation inside the oven, and reflecting the waves back inside.

This is actually also why the window into microwave ovens have that mesh film on the inside; the microwaves are too large to make it through the holes in the mesh. This keeps the radiation in, but still allows us to see the hot cocoa inside.

The actual microwaves are produced in something called a magnetron. The magnatron consists of a cathode in the center with an anode surrounding it. The anode contains in it, however, small cavities called resonate cavities where electrons become manipulated to form electron bunches. These bunches then move at microwave frequencies and lead to oscillations in the resonate cavities.

After that the microwaves are fed through the waveguide into the cooking chamber to heat the cocoa.

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