Eli5: What does the frequency (Hz) have to do with electrical output? If the world has 50/60 Hz frequency for their outlets, what exactly does that mean/do? Is it as simple as if it goes below/exceeds the specified frequency it just gives/reduces power output or something different?
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We use AC power on the power lines. This is current that is generated in a way where it literally alternates between positive and negative voltages over time. That’s what 50Hz and 60Hz refer to: how many times per second the voltage alternates.
We chose to use AC for our power because it’s better at being transferred over long distances without losing a lot of energy. The physics behind this are weird and complicated but the main difference is if you run AC through a long wire you get “an electric field” and if you run DC through a long wire you have probably made “an electric heater”.
But DC is what almost all electronic devices need to run. There are devices that can convert AC to DC. The way this works is best if you can see how the electricity’s voltage changes on a graph, but there’s not a good way to do that on reddit.
A good AC electrical signal looks like a sine wave, go look that up on a search engine. You’ll see it’s a smooth curve between 0, some maximum positive value, 0 again, and some minimum negative value. In US households we are connected to power sources that alternate between +120 and -120V at a rate of 60Hz (I’m telling a small lie here that doesn’t matter in the big picture.)
The things that convert AC to DC tend to only deal with the positive part of that sine wave. So that means they only have any voltage at all for half of a second, and for most of that half of a second they don’t have the full power. So they rely on electrical components that sort of act like batteries, store the power from the wave, and release a smaller but steady voltage to the rest of the device. (A lot of the extra power ends up getting released as heat, which is why a lot of chargers and other devices get hot while in use!)
Using water as an analogy helps. Imagine you have a weird water supply that provides full-pressure water for 1 second, then no water for 1 second, and keeps going back and forth. That’s not great for brushing your teeth. But you can design a water tank that stores up the water and, after it fills up, provides you with a constant stream of pressurized water so long as you don’t try to use more than is being pumped in. That’s more or less what AC -> DC converters do.
But think about what happens if your water company suddenly changes the pattern after you design that system. If they add more time without water, your tank won’t stay as full and might not be able to give you a steady water flow for long enough to brush your teeth. If they add more time with pressurized water, your tank might get overfilled and any pressure relief valves you added won’t be sufficient. So it’s important the water company delivers exactly the rate of water they promise and don’t change their mind.
The same is true of DC -> AC converters. The cycle rate of the electricity affects how the power is converted, and having too slow or too fast of a cycle can either not work at all or give too much power to the device and damage it.
Some stuff in your house just uses AC power directly (most stuff with motors will.) The problem with changing the cycle is they’ll spin at different speeds based on how the cycle changed, a vacuum that spins too slow won’t work as well, and you can imagine trying to spin motors faster than they were designed to spin might not always end well.
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