Name: Electric potential charge configuration | Physics | Khan Academy
Uploaded: 2022-07-19T03:08:59.000Z
Duration: 5 min 21 s
Description: VoiceTubeの動画で発音を聞きながら英語表現を覚えよう！学べる英語：

過去形

- [Instructor] So imagine you had three charges

sitting next to each other, but they're fixed in place.

or secured in place, we're not gonna let'em move.

But we do know the values of the charges.

We've got a positive one microcoulomb charge,

So a question that's often asked when you have this type

of scenario is if we know the distances between the charges,

what's the total electric potential at some point,

So we want to know what's the electric potential at point P.

Since we know where every charge is that's gonna be

we can just use the formula for the electric potential

created by a charge and that formula is V equals k,

the charge creating the electric potential divided by r

which is the distance from the charge to the point

where it's creating the electric potential.

all creating electric potential at point P.

And to do that, we can just find the electric potential

that each charge creates at point P, and then add them up.

So in other words, this positive one microcoulomb charge

is gonna create an electric potential value at point P,

and we can use this formula to find what that value is.

So we get the electric potential from the

positive one microcoulomb charge, it's gonna equal k,

which is always nine times 10 to the ninth,

times the charge creating the electric potential

which in this case is positive one microcoulombs.

Micro means 10 to the negative six and the distance

between this charge and the point we're considering

to find the electric potential is gonna be four meters.

So from here to there, we're shown is four meters.

And we get a value 2250 joules per coulomb,

But this is just the electric potential created at point P

by this positive one microcoulomb charge.

All the rest of these charges are also gonna create

So if we want the total electric potential,

we're gonna have to find the contribution

from all these other charges at point P as well.

positive five microcoulomb charge is gonna also be

nine times 10 to the ninth, but this time,

I'm not gonna use three meters or four meters

to the point where it's creating the electric potential.

And that's gonna be this distance right here.

To find the length of this side, you can just do

three squared plus four squared, take a square root,

So this is five meters from this charge to this point P.

this negative two microcoulombs is also gonna create

will again be nine times 10 to the ninth.

This time, times negative two microcoulombs.

Again, it's micro, so 10 to the negative six,

but notice we are plugging in the negative sign.

Negative charges create negative electric potentials

at points in space around them, just like positive charges

create positive electric potential values

So you've got to include this negative, that's the bad news.

You've gotta remember to include the negative.

Electric potential is not a vector quantity.

So I'm not gonna have to break this into components

or worry about anything like that up here.

These are all just numbers at this point in space.

And to find the total, we're just gonna add all these up

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Electric potential charge configuration | Physics | Khan Academy

literally

awkward

potential

scenario