so when you get your home energy bill it
lists the usage in kilowatt hours but
when you go to the store you'll see things like 12 watt light bulbs 9 volt
batteries and vacuum cleaners with 15
amps of sucking power but what do these numbers even mean i
mean why do we have so many different units
to measure something that seems as straightforward as electricity
surprisingly the answer isn't just so appliance companies and physics
professors can confuse you it's because several important things have to happen
in an electrical circuit for electricity to flow and for work to be done
you can think of a circuit kind of like the faucet on your kitchen sink if you
want water to come out you need two things you need the water itself and
some pressure to force it through the pipes outer faucet and into your neti
pot similarly an electrical circuit uses
electrons to carry the electricity kind of like the water in our faucet analogy
but those electrons need something to push them along a circuit this
electrical pressure is what we call voltage and is often provided by two
terminals one with a positive charge and
one with a negative charge so on a
battery electrons flow from the negative
end through whatever it is you're trying to power and then into the positive end
where they'll stay unless your battery is rechargeable if you're plugging
something into the wall this voltage is instead provided by your power company
and although voltage just measures how
strongly electricity is being pushed through a circuit it's important because
many circuits are designed only to accept a certain number of volts
which is why the hair dryer you bought in monaco might release magic blue smoke
if you plug it in in new york so now that you know what volts are what
about amps well in this context amp isn't short for
amplifier but rather for ampere which is a unit of
how much electrical charge is flowing past a given point in one second so when
you put volts and amps together you can
tell how much current is flowing and how
hard it's flowing multiply these numbers and you get
finally our third unit the watt
let's go back to our water analogy for a second let's suppose you wanted to spin
a small water wheel because you just like
watching things spin or i don't know maybe you have it hooked up to a generator
let's say you have a really powerful water pistol that forces water through a
tiny nozzle even though the small nozzle means the
total volume of water flowing per second
isn't all that much you wouldn't want to feel your swimming pool with it the high
pressure creates a strong jet that can
spin the wheel easily but suppose instead of a water gun you have a much
wider hose that doesn't push the water out nearly as strongly but because the
hose is a lot wider more water flows per
second overall and the wheel ends up spinning at the same speed it did with
your water gun if we think of the hose
and the water gun pushing out electricity instead of water we could
say that they're delivering the same number of watts
for a more practical example let's say you have an 1100 watt power supply for
your computer that's drawing full load because you're rocking four-way sli or
something so if you plug that into a standard 110 volt north american outlet
some simple math tells you that 10 amps of current is running through your power
supply but if you take that same power supply and use it with a 220 volt
european outlet you're only drawing 5 amps but since the amount of power in
watts is the same your computer will work just fine in both places even
though you're using different volts and amps well that makes sense Linus but why
the heck then is my energy bill in kilowatt hours is that a unit of time no
actually scientists are just mean it's a unit of energy watts and kilowatts
express how much energy is consumed per chunk of time something scientists call
power which is not the same as energy but if you multiply a kilowatt by an
hour the units cancel and you're left with a number that shows how much energy
that you hogged by running your air conditioner gaming rig and novelty lava
lamp all at once but what if you're more concerned about
battery capacity instead of what's
coming out of your walls well if you're buying a replacement battery or a
battery pack you might see their capacity listed in milliamp hours again
not time doing the math shows that this is a unit of charge not energy or power
so going back to our water example this
is like how much water you have in a bucket not how much is flowing or how
fast is flowing so a bigger bucket means you could charge your phone more times
and you can learn more about that and battery banks in this video here
so go forth then with your newfound knowledge and expertly buy the right
voltage adapter install the correct power supply or just ace your electrical
engineering exam if you want to do more with your life than work for some
second-rate youtube channel but wait what
hey john second-rate youtube channel like is that supposed to be a joke it's
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thanks for watching guys like dislike check out our other channels comment
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