# eli5 Why do some appliances consume more power than others where it all get an input of 220v / 110v?

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eli5 Why do some appliances consume more power than others where it all get an input of 220v / 110v?

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Why does a fire hydrant release so much more water than your kitchen faucet? They are both getting water at the same pressure.

Voltage is like water pressure. It’s one of the big factors in power consumption, but not the only one. How much current the device uses is the other, and it’s just as important. (I’m simplifying a bit, but not too much.)

Power is a product of voltage and current.

You can think of it using the water flow analogy: voltage is water pressure in the pipe, current is the size of the pipe, power is the volumetric flow rate, and energy is the amount of water moved.

The standard US outlet can do 15A @ 120V, but each appliance will only draw as much current as it needs (inversely proportional to its resistance given a fixed voltage).

So an appliance can draw anywhere between 0 and 15A (before it trips your breaker if it’s up to code), and can therefore dissipate anywhere between 0 and 1800W.

Voltage doesn’t come pushing out of the socket. It just sits there stupidly doing nothing. Then somebody plugs in a toaster and the earth sucks the electricity and sucks hard through the little toaster wires, pulling the juice out of the wall. The earth sucks so hard the electricity jams up in the toaster and those skinny little wires get real hot. Heaters suck up a lot and get hot. LED light just sip a little juice and don’t get all jammed up full of electrons and hot. Like that.

if a divice consumes the current it needs automatically, why is it automatically? does it consume just what it needs? sorry for bad english

It’s the same reason the entire reservoir doesn’t come tearing out of your kitchen tap when you go to do the dishes.

How much flow happens is limited by the thing consuming the flow. In the case of electricity it’s the device, if it’s water, it’s your tap. How large it is, how far open it is.