We all knew that kid in grade school who
the teacher said had so much potential
and what that meant is that they could
be something great someday if they
applied themselves, but at that point in
time they weren't necessarily acting
that way. That's actually a lot like
voltage. Stick around and find out why!
Hi I'm Daniel Bogdanoff. Welcome to the
2-Minute Guru. Today we're going to talk
about voltage. Voltage is simply the
difference in electrical potential
energy between two points. A quick
clarification - electric potential energy
has to do with particles themselves, like
electrons and ions. It's measured in
Joules whereas electrical potential is
measured in Joules/Coulomb and it
has to do with the electric field itself.
The charge of the particles themselves is
measured in Coulombs, so if you take the
electrical potential energy and divide
it by the charge of the particle itself,
all you're left with is that energy in
space- the electrical potential. And Volts
are measured in Joules/Coulomb.
So all this to say that all voltage
measurements and values are simply a
difference in electric potential between
two points in space. So when I say that
this is a 9 volt battery, what that
means is that there's 9 volts of
electric potential between the two
terminals. The analogy I like to use for
voltage is gravity, or more specifically,
physical potential energy. Think back to
Physics I. If I pick up this ball, it
now has potential energy with respect to
the ground or whatever I choose to
compare to. Let's say I'm going to
compare the potential energy between
these two balls. I'll name this one
"positive" because I can and this one
"ground." And I've given it a nifty little
ground symbol here. Right now there's no
difference in potential energy but as
soon as I pick up one of these balls,
there's now a difference in potential
energy with respect to each other. When
it comes to electricity, instead of
height, we have electrical potential
energy levels. Typically we measure with
respect to ground which we consider to
be zero volts. Whether or not that's
actually true is another discussion.
Ground (or zero volts) used to be, and
sometimes still is, a metal rod hammered
into the ground, but if you take a
spaceship, for example, they still have a
zero volt ground reference even though
by definition a spaceship cannot have a
metal rod pounded into the ground. Also
notice that unlike current,
no movement is required for there to be
a voltage. This ball could fall because
there's a constant pull from gravity, but
my hand is blocking the path. As soon as
there's a path, the ball is going to fall
and there's current. Take this 9-volt
battery for example. Even though there's
no current path flowing I'm still
measuring over 9 volts between the two
terminals on the battery with my oscilloscope, and that's
because I'm using the oscilloscope to compare
the negative terminal to the positive terminal. And I
expect that to be 9 volts since it's,
well, a 9-volt battery. That's all we have
time for today. Thanks for watching! If
this video is helpful, hit the share
button, hit the thumbs up button. If
there's any topics you want me to cover
in the future, put them in the comments
below. I'm Daniel Bogdanoff and I'll
see you in two weeks.


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