WEBVTT

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so when you get your home energy bill it

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lists the usage in kilowatt hours but

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when you go to the store you'll see things like 12 watt light bulbs 9 volt

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batteries and vacuum cleaners with 15

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amps of sucking power but what do these numbers even mean i

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mean why do we have so many different units

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to measure something that seems as straightforward as electricity

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surprisingly the answer isn't just so appliance companies and physics

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professors can confuse you it's because several important things have to happen

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in an electrical circuit for electricity to flow and for work to be done

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you can think of a circuit kind of like the faucet on your kitchen sink if you

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want water to come out you need two things you need the water itself and

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some pressure to force it through the pipes outer faucet and into your neti

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pot similarly an electrical circuit uses

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electrons to carry the electricity kind of like the water in our faucet analogy

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but those electrons need something to push them along a circuit this

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electrical pressure is what we call voltage and is often provided by two

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terminals one with a positive charge and

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one with a negative charge so on a

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battery electrons flow from the negative

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end through whatever it is you're trying to power and then into the positive end

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where they'll stay unless your battery is rechargeable if you're plugging

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something into the wall this voltage is instead provided by your power company

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and although voltage just measures how

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strongly electricity is being pushed through a circuit it's important because

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many circuits are designed only to accept a certain number of volts

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which is why the hair dryer you bought in monaco might release magic blue smoke

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if you plug it in in new york so now that you know what volts are what

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about amps well in this context amp isn't short for

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amplifier but rather for ampere which is a unit of

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how much electrical charge is flowing past a given point in one second so when

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you put volts and amps together you can

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tell how much current is flowing and how

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hard it's flowing multiply these numbers and you get

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finally our third unit the watt

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let's go back to our water analogy for a second let's suppose you wanted to spin

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a small water wheel because you just like

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watching things spin or i don't know maybe you have it hooked up to a generator

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let's say you have a really powerful water pistol that forces water through a

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tiny nozzle even though the small nozzle means the

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total volume of water flowing per second

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isn't all that much you wouldn't want to feel your swimming pool with it the high

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pressure creates a strong jet that can

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spin the wheel easily but suppose instead of a water gun you have a much

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wider hose that doesn't push the water out nearly as strongly but because the

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hose is a lot wider more water flows per

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second overall and the wheel ends up spinning at the same speed it did with

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your water gun if we think of the hose

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and the water gun pushing out electricity instead of water we could

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say that they're delivering the same number of watts

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for a more practical example let's say you have an 1100 watt power supply for

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your computer that's drawing full load because you're rocking four-way sli or

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something so if you plug that into a standard 110 volt north american outlet

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some simple math tells you that 10 amps of current is running through your power

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supply but if you take that same power supply and use it with a 220 volt

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european outlet you're only drawing 5 amps but since the amount of power in

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watts is the same your computer will work just fine in both places even

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though you're using different volts and amps well that makes sense Linus but why

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the heck then is my energy bill in kilowatt hours is that a unit of time no

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actually scientists are just mean it's a unit of energy watts and kilowatts

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express how much energy is consumed per chunk of time something scientists call

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power which is not the same as energy but if you multiply a kilowatt by an

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hour the units cancel and you're left with a number that shows how much energy

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that you hogged by running your air conditioner gaming rig and novelty lava

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lamp all at once but what if you're more concerned about

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battery capacity instead of what's

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coming out of your walls well if you're buying a replacement battery or a

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battery pack you might see their capacity listed in milliamp hours again

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not time doing the math shows that this is a unit of charge not energy or power

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so going back to our water example this

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is like how much water you have in a bucket not how much is flowing or how

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fast is flowing so a bigger bucket means you could charge your phone more times

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and you can learn more about that and battery banks in this video here

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so go forth then with your newfound knowledge and expertly buy the right

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voltage adapter install the correct power supply or just ace your electrical

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engineering exam if you want to do more with your life than work for some

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second-rate youtube channel but wait what

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hey john second-rate youtube channel like is that supposed to be a joke it's

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not funny speaking of things that are no joke

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through up to 20 different countries well one at a time but allowing you to

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and when you turn it on two things happen your connection gets encrypted

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then head over to tunnelbear.com Linus and save that money

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thanks for watching guys like dislike check out our other channels comment

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with video suggestions and don't forget to subscribe

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i think that's the fastest one i've done yet though i might have negated all the time

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