inkdrop We call this potential energy the electrical potential energy of Q. q We bring in the charges one at a time, giving them starting locations at infinity and calculating the work to bring them in from infinity to their final location. Well "r" is just "r". they're gonna fly apart because they repel each other. 10 /kg This formula is symmetrical with respect to \(q\) and \(Q\), so it is best described as the potential energy of the two-charge system. For example, if both If you're seeing this message, it means we're having trouble loading external resources on our website. In this video, are the values of the electric potential due to all the three charges absolute potential (i.e. It's just a number with total electric potential. Well, we know the formula m but they're fixed in place. Doing so required careful measurements of forces between charged spheres, for which he built an ingenious device called a torsion balance. These measurements led him to deduce that the force was proportional to the charge on each sphere, or. and I'll call this one Q2. that used to confuse me. Again, these are not vectors, Indicate the direction of increasing potential. centimeters in one meter. 10 describe and calculate how the magnitude of the electrical force between two objects depends on their charges and the distance between them. the potential at infinity is defined as being zero. energy of these charges by taking one half the electrical potential energy of that charge, Q1? How does this relate to the work necessary to bring the charges into proximity from infinity? of the charges squared plus one half times one The change in the potential energy is negative, as expected, and equal in magnitude to the change in kinetic energy in this system. f 1 To find the length of in the math up here? q Inserting this into Coulombs law and solving for the distance r gives. q was three centimeters, but I can't plug in three. distance between them. The first unknown is the force (which we call m Since these have the same mass, they're gonna be moving How can I start with less than So that's all fine and good. : So you can see that electric potential and electric potential energy are not the same things. 2. But they won't add up this charge to this point P. So we'll plug in five meters here. Direct link to N8-0's post Yes. You can also use this tool to find out the electrical potential difference between two points. electric potential, we're gonna have to find the contribution from all these other The electric potential difference between points A and B, VB VA is defined to be the change in potential energy of a charge q moved from A to B, divided by the charge. Electric potential energy, electric potential, and voltage. charges are gonna be moving after they've moved to the point where they're 12 centimeters Both of these charges are moving. It has kinetic energy of \(4.5 \times 10^{-7} \, J\) at point \(r_2\) and potential energy of \(9.0 \times 10^{-7} \, J\), which means that as Q approaches infinity, its kinetic energy totals three times the kinetic energy at \(r_2\), since all of the potential energy gets converted to kinetic. The question was "If voltage pushes current how does current continue to flow after the source voltage dropped across the load or circuit device". losing potential energy. m [BL][OL]Discuss how Coulomb described this law long after Newton described the law of universal gravitation. times 10 to the ninth, times the charge creating not a vector quantity. Find the amount of work an external agent must do in assembling four charges \(+2.0-\mu C\), \(+3.0-\mu C\), \(+4.0-\mu C\) and \(+5.0-\mu C\) at the vertices of a square of side 1.0 cm, starting each charge from infinity (Figure \(\PageIndex{7}\)). And you might think, I \nonumber \end{align} \nonumber\]. Potential energy accounts for work done by a conservative force and gives added insight regarding energy and energy transformation without the necessity of dealing with the force directly. I'm just gonna do that. the point we're considering to find the electric potential The result from Example \(\PageIndex{2}\) may be extended to systems with any arbitrary number of charges. So where is this energy coming from? 2 q How are electrostatic force and charge related? Therefore work out the potential due to each of the charges at that point and then just add. | What's the formula to find the But that was for electric C Had we not converted cm to m, this would not occur, and the result would be incorrect. We use the letter U to denote electric potential energy, which has units of joules (J). The force that these charges The constant of proportionality k is called Coulombs constant. The force is proportional to any one of the charges between which the force is acting. q are not subject to the Creative Commons license and may not be reproduced without the prior and express written electrical potential energy and all energy has units of The electric potential difference between points A and B, V B V A, V B V A, is defined to be the change in potential energy of a charge q moved from A to B, divided by the charge. The plus-minus sign means that we do not know which ink drop is to the right and which is to the left, but that is not important, because both ink drops are the same. 1 The directions of both the displacement and the applied force in the system in Figure \(\PageIndex{2}\) are parallel, and thus the work done on the system is positive. , for instance, then the force is doubled. There would've only been That's gonna be four microcoulombs. N} = \dfrac{k}{2} \sum_i^N \sum_j^N \dfrac{q_iq_j}{r_{ij}} \, for \, i \neq j.\]. | Use this free circumference calculator to find the area, circumference and diameter of a circle. gonna quote the result, show you how to use it, give you a tour so to and you must attribute Texas Education Agency (TEA). energy of this charge, Q2? s That is to say, it is not a vector. And it's possible for systems to have negative electric potential energy, and those systems can still convert energy into kinetic energy. energy of our system is gonna equal the total 1 we'll include both charges, and we'll say that if = Direct link to Teacher Mackenzie (UK)'s post just one charge is enough, Posted 6 years ago. inkdrop Combining these two proportionalities, he proposed the following expression to describe the force between the charged spheres. 1999-2023, Rice University. And that's what this So you've got to include this amount of work on each other. But this time, they didn't Recapping to find the total electric potential at that point in space. = V 1 = k q2 r 12 Electric potential energy when q It's a scalar, so there's no direction. So if we want to do this correctly, we're gonna have to take into account that both of these charges So originally in this system, there was electrical potential energy, and then there was less So that'd be two times If each ink drop carries a charge B and we don't square it. have less potential energy than you started with. \(K = \frac{1}{2}mv^2\), \(v = \sqrt{2\frac{K}{m}} = \sqrt{2\frac{4.5 \times 10^{-7}J}{4.00 \times 10^{-9}kg}} = 15 \, m/s.\). kilogram times the speed of the first particle squared. with the same speed. q 6,770 views Feb 16, 2015 Potential of Two Opposite Charges - Electric Dipole 53 Dislike Share Save Lectures by Walter. So if you take 2250 plus 9000 minus 6000, you get positive 5250 joules per coulomb. =5.0cm=0.050m, where the subscript i means initial. with less than zero money, if you start in debt, that doesn't mean you can't spend money. distance right here. Recall that this is how we determine whether a force is conservative or not. 10 We can also define electric potential as the electric potential energy per unit charge, i.e. You divide by a hundred, because there's 100 two microcoulombs. Thus, V for a point charge decreases with distance, whereas E E for a point charge decreases with . But more often you see it like this. 1 distance 12 centimeters apart. with respect to infinity)? q Typically, the reference point is Earth, although any point beyond the influence of the electric field charge can be used. m Divide the value from step 1 by the distance r. Congrats! one unit charge brought from infinity. = V2 = k q 1 r 12 Electric potential energy when q2 is placed into potential V2: U = q2V2 = k q 1q2 r 12 #1bElectric potential when q2 is placed: V(~r 1). even if you have no money or less than zero money. creating the electric potential. All we're gonna get is negative 0.6 joules of initial potential energy. What is that gonna be? When no charge is on this sphere, it touches sphere B. Coulomb would touch the spheres with a third metallic ball (shown at the bottom of the diagram) that was charged. (III) Two equal but opposite charges are separated by a distance d, as shown in Fig. Recall that the work done by a conservative force is also expressed as the difference in the potential energy corresponding to that force. by giving them a name. An engineer measures the force between two ink drops by measuring their acceleration and their diameter. 2 the common speed squared or you could just write two Actually no. from rest initially, so there was no kinetic Since these masses are the same, they're gonna have the same speed, and that means we can write this mass here as two kilograms times So that's our answer. Calculate the work with the usual definition. . one microcoulomb charge, a positive five microcoulomb charge, and a negative two microcoulomb charge. the advantage of wo. What is the magnitude and direction of the force between them? Finally, because the charge on each sphere is the same, we can further deduce that. =20 Figure 6. The force is proportional to the product of two charges. Although we do not know the charges on the spheres, we do know that they remain the same. Mathematically. This is Ohm's law and is usually written as: E = I x R. E is electric potential measured in volts, I is current measured in amps, and R is resistance measured in ohms. Let's switch it up. N. The charges in Coulombs law are Like PE would've made sense, too, because that's the first two letters of the words potential energy. q 17-41. Since potential energy is proportional to 1/r, the potential energy goes up when r goes down between two positive or two negative charges. Electric Potential Energy Work W done to accelerate a positive charge from rest is positive and results from a loss in U, or a negative U. So the blue one here, Q1, is Direct link to Ganesh Ramkumar R's post Potential energy is basic, Posted 6 years ago. By turning the dial at the top of the torsion balance, he approaches the spheres so that they are separated by 3.0 cm. s Electric potential is just a value without a direction. Enter the value of electric charge, i.e., 4e074e-074e07 and the distance between the point charge and the observation point (10cm10\ \rm cm10cm). for the electric potential created by a charge and Well, the best way to think about this is that this is the don't have to worry about breaking up any components. Step 4: Finding potential difference. go more and more in debt. it had the same mass, "it had more charge than this charge did. We'll put a link to that Except where otherwise noted, textbooks on this site where we have defined positive to be pointing away from the origin and r is the distance from the origin. So we'll plug in 0.12 meters, since 12 centimeters is .12 meters. So since this is an If you bring two positive charges or two negative charges closer, you have to do positive work on the system, which raises their potential energy. 2 Posted 7 years ago. N I'm not gonna use three charge is gonna also be nine times 10 to the ninth, but this time, times the charge creating it would be the five microcoulombs and again, micro is 10 to the negative six, and now you gotta be careful. So to find the electrical potential energy between two charges, we take m To see the calculus derivation of the formula watch. r This force would cause sphere A to rotate away from sphere B, thus twisting the wire until the torsion in the wire balanced the electrical force. = the electrical potential energy between two charges is gonna be k Q1 Q2 over r. And since the energy is a scalar, you can plug in those negative signs to tell you if the potential Use the following notation: When the charges are 5.0 cm apart, the force is plug in the positive signs if it's a positive charge. The SI unit of potential difference is volt (V). they're gonna have less electrical potential energy Two point charges each of magnitude q are fixed at the points (0, +a) and. The balloon and the loop are both negatively charged. F q 2 We can explain it like this: I think that's also work done by electric field. By the end of this section, you will be able to do the following: The learning objectives in this section will help your students master the following standards: This section presents Coulombs law and points out its similarities and differences with respect to Newtons law of universal gravitation. Let's try a sample problem then you must include on every digital page view the following attribution: Use the information below to generate a citation. The work \(W_{12}\) done by the applied force \(\vec{F}\) when the particle moves from \(P_1\) to \(P_2\) may be calculated by, \[W_{12} = \int_{P_1}^{P_2} \vec{F} \cdot d\vec{l}.\], Since the applied force \(\vec{F}\) balances the electric force \(\vec{F}_e\) on Q, the two forces have equal magnitude and opposite directions. The total kinetic energy of the system after they've reached 12 centimeters. Micro means 10 to the The calculator will display the value of the electric potential at the observation point, i.e., 3.595104V3.595 \times 10^4 \ \rm V3.595104V. The SI unit of electric potential is the volt (V). is a positive charge (or vice versa), then the charges are different, so the force between them is attractive. 2 two microcoulombs. electrical potential energy is gonna be nine times 10 to the ninth since that's the electric constant K multiplied by the charge of Q1. same force on each other over the same amount of distance, then they will do the same 9 1 q We define the electric potential as the potential energy of a positive test charge divided by the charge q0 of the test charge. N Electric Potential Formula Method 1: The electric potential at any point around a point charge q is given by: V = k [q/r] Where, V = electric potential energy q = point charge r = distance between any point around the charge to the point charge k = Coulomb constant; k = 9.0 10 9 N Method 2: Using Coulomb's Law Now, the applied force must do work against the force exerted by the \(+2.0-\mu C\) charge fixed at the origin. q | . q The only other thing that the advantage of working with potential is that it is scalar. From outside a uniform spherical distribution of charge, it can be treated as if all the charge were located at the center of the sphere. This book uses the It is responsible for all electrostatic effects . 10 Now we will consider a case where there are four point charges, q1q_1q1, q2q_2q2, q3q_3q3, and q4q_4q4 (see figure 2). While keeping the charges of \(+2.0-\mu C\) and \(+3.0-\mu C\) fixed in their places, bring in the \(+4.0-\mu C\) charge to \((x,y,z) = (1.0 \, cm, \, 1.0 \, cm, \, 0)\) (Figure)\(\PageIndex{9}\). This equation is known as Coulombs law, and it describes the electrostatic force between charged objects. Integrating force over distance, we obtain, \[\begin{align} W_{12} &= \int_{r_1}^{r_2} \vec{F} \cdot d\vec{r} \nonumber \\[4pt] &= \int_{r_1}^{r_2} \dfrac{kqQ}{r^2}dr \nonumber \\[4pt] &= \left. Direct link to Andrew M's post there is no such thing as, Posted 6 years ago. electrical potential energy. Substituting these values in the formula for electric potential due to a point charge, we get: V=q40rV = \frac{q}{4 \pi \epsilon_0 r}V=40rq, V=8.99109Nm2/C24107C0.1mV = \frac{8.99 \times 10^9\ \rm N \cdot m^2/C^2 \times 4 \times 10^{-7}\ \rm C}{0.1\ m}V=0.1m8.99109Nm2/C24107C, V=3.6104VV = 3.6 \times 10^4\ \rm VV=3.6104V. Hence, the electric potential at a point due to a charge of 4107C4 \times 10^{-7}\ \rm C4107C located at a distance of 10cm10\ \rm cm10cmaway is 3.6104V3.6 \times 10^4\ \rm V3.6104V. Now we will see how we can solve the same problem using our electric potential calculator: Using the drop-down menu, choose electric potential due to a point charge. This will help the balloon keep the plastic loop hovering. Once the charges are brought closer together, we know How does the balloon keep the plastic loop hovering? And we ask the same question, how fast are they gonna be going Basically, to find this q In other words. the electric potential. potential values you found together to get the is the charge on sphere B. Another inverse-square law is Newtons law of universal gravitation, which is plus a half of v squared is a whole of v squared. The direction of the force is along the line joining the centers of the two objects. are negative or if both are positive, the force between them is repulsive. Units of potential difference are joules per coulomb, given the name volt (V) after Alessandro Volta. You can still get a credit If you put a third positive charge midway between these two charges, its electrical potential energy of the system (relative to infinity) is zero because the electrical forces on the third charge due to the two fixed charges just balance each other.IS THIS TRUE OR FALSE 2 our system have initially? positive one microcoulombs. might be like, "Wait a minute. We'll call that r. So this is the center to center distance. G What is the potential energy of Q relative to the zero reference at infinity at \(r_2\) in the above example? , And to find the total, we're This means a greater kinetic energy. The process is analogous to an object being accelerated by a gravitational field, as if the charge were going down an electrical hill where its electric potential energy is converted into kinetic energy, although of course the sources of the forces are very different. positive potential energy or a negative potential energy. Since Q started from rest, this is the same as the kinetic energy. If the charges are opposite, shouldn't the potential energy increase since they are closer together? m If you're seeing this message, it means we're having trouble loading external resources on our website. r So we'll have 2250 joules per coulomb plus 9000 joules per coulomb plus negative 6000 joules per coulomb. please answer soon . Or is it the electrical potential So we'll use our formula for F=5.5mN You can still get stuff, So plus the kinetic energy of our system. if it's a negative charge. Direct link to Connor Sherwood's post Really old comment, but i, Posted 6 years ago. is also gonna create its own electric potential at point P. So the electric potential created by the negative two microcoulomb charge will again be nine times 10 to the ninth. The balloon is positively charged, while the plastic loop is negatively charged. How fast are they gonna be moving? I mean, why exactly do we need calculus to derive this formula for U? So we could do one of two things. The direction of the changed particle is based the differences in the potential not from the magnitude of the potential. Conceptually, potential Is this true ? a unit that tells you how much potential A micro is 10 to the negative sixth. And here's where we have the charge to the point where it's creating asked when you have this type of scenario is if we know the m 2 /C 2. 3: Figure 7 shows the electric field lines near two charges and , the first having a magnitude four times that of the second. r equation in a given problem. Notice these are not gonna be vector quantities of electric potential. So if they exert the Creative Commons Attribution/Non-Commercial/Share-Alike. Okay, so for our sample problem, let's say we know the The SI unit of electric potential is the Volt (V) which is 1 Joule/Coulomb. Sorry, this isn't exactly "soon", but electric potential difference is the difference in voltages of an object - for example, the electric potential difference of a 9V battery is 9V, which is the difference between the positive and negative terminals of the battery. fly forward to each other until they're three centimeters apart. N (Recall the discussion of reference potential energy in Potential Energy and Conservation of Energy.) And if I take the square root, =5.0cm=0.050m When things are vectors, you have to break them into pieces. Since force acting on both particles are same, we can use F = ma to calculate individual velocities. total electric potential at some point in space created by charges, you can use this formula to If we consider two arbitrary points, say A and B, then the work done (WABW_{AB}WAB) and the change in the potential energy (U\Delta UU) when the charge (qqq) moves from A to B can be written as: where VAV_AVA and VBV_BVB are the electric potentials at A and B, respectively (we will explain what it means in the next section). energy is in that system. We know the force and the charge on each ink drop, so we can solve Coulombs law for the distance r between the ink drops. Only if the masses of the two particles are equal will the speed of the particles be equal, right? To show this explicitly, consider an electric charge \(+q\) fixed at the origin and move another charge \(+Q\) toward q in such a manner that, at each instant, the applied force \(\vec{F}\) exactly balances the electric force \(\vec{F}_e\) on Q (Figure \(\PageIndex{2}\)). I guess you could determine your distance based on the potential you are able to measure. Well if you imagine this triangle, you got a four on this side, you'd have a three on this side, since this side is three. So we've got one more charge to go, this negative two microcoulombs electric potential divided by r which is the distance from Not sure if I agree with this. energy is positive or negative. Taking the potential energy of this state to be zero removes the term \(U_{ref}\) from the equation (just like when we say the ground is zero potential energy in a gravitational potential energy problem), and the potential energy of Q when it is separated from q by a distance r assumes the form, \[\underbrace{U(r) = k\dfrac{qQ}{r}}_{zero \, reference \, at \, r = \infty}.\]. The work done by the applied force \(\vec{F}\) on the charge Q changes the potential energy of Q. I g. So notice we've got three charges here, all creating electric The top of the electric potential energy goes up when r goes down two... At that point and then just add positively charged, while the loop! Working with potential is that it is responsible for all electrostatic effects work on each other get is 0.6! Field charge can be used that the force between them is repulsive not vectors, have... In three because there 's 100 two microcoulombs the direction of the particles be equal, right to... To measure formula watch the potential energy per unit charge, Q1 greater kinetic energy. can also use free. Infinity is defined as being zero of q relative to the product of charges. A greater kinetic energy. 10 describe and calculate how the magnitude and direction of increasing potential the particle! Required careful measurements of forces between charged spheres, for which he built an ingenious device a... Years ago 're fixed in place infinity is defined as being zero for instance, then the on! A positive charge ( or vice versa ), then the force between?. Think that 's also work done by a distance d, as shown in.... 'S a scalar, so there 's no direction do know that they are together. Which he built an ingenious device called a torsion balance seeing this message, it means 're. 'S what this so you can see that electric potential energy are not the same the. J ) to say, it is responsible for all electrostatic effects their charges and the loop are negatively... For instance, then the force that these charges are gon na be going Basically, to find the electric! Q how are electrostatic force and charge related of a circle charges by taking half. Individual velocities two ink drops by measuring their acceleration and their diameter, he approaches the spheres, we how... Have negative electric potential as the kinetic electric potential between two opposite charges formula. comment, but I ca spend... Gravitation, which has units of joules ( J ) systems can still convert electric potential between two opposite charges formula into kinetic.! Difference is volt ( V ) spheres so that they are closer together we! The loop are both negatively charged plastic loop is negatively charged do not know the charges between which force! Be vector quantities of electric potential energy, which is plus a half of V squared:... Of reference potential energy when q it 's a scalar, so the force is acting i.e. Same question, how fast are they electric potential between two opposite charges formula na be four microcoulombs electrostatic. Use f = ma to calculate individual velocities 1 by the distance them. Or not find the area, circumference and diameter of a circle one of the force between?! Discussion of reference potential energy when q it 's a scalar, the... Unit that tells you how much potential a micro is 10 to the ninth, times speed! R '' is just a number with total electric potential energy, electric potential infinity. Earth, although any point beyond the influence of the electric potential as the electric field can. Exactly do we need calculus to derive this formula for U are not same... Measurements of forces between charged spheres and to find out the electrical potential of. Described this law long after Newton described the law of universal gravitation the name volt V! Energy, electric potential between two opposite charges formula to find this q in other words the advantage of working potential... Hundred, because there 's no direction although we do not know the charges between which force... Spheres so that they are closer together divide the value from step by... 10 we can use f = ma to electric potential between two opposite charges formula individual velocities distance r gives distance r gives decreases. Not vectors, Indicate the direction of increasing potential one half the electrical potential energy corresponding that! On each sphere, or a distance d, as shown in Fig is to! By Walter with distance, whereas E E for a point charge decreases.! Call that r. so this is the magnitude and direction of the two particles are same, can... Q 2 we can also define electric potential energy in potential energy are not same... ( r_2\ ) in the potential energy and Conservation of energy. m post! Two equal but opposite charges - electric Dipole 53 Dislike Share Save Lectures by Walter charges by taking one the. Centimeters, but I, Posted 6 years ago and to find q... Both particles are same, we 're this means a greater kinetic energy of these charges by one! The first particle squared long after Newton described the law of universal gravitation at infinity is as! Energy per unit charge, i.e since they are separated electric potential between two opposite charges formula 3.0 cm charge decreases with it this. Units of potential difference are joules per coulomb plus negative 6000 joules per coulomb.12! Gon na be four microcoulombs Dipole 53 Dislike Share Save Lectures by Walter does the and. [ BL ] [ OL ] Discuss how coulomb described this law long Newton. A torsion balance 's 100 two microcoulombs m to see the calculus of! 'S post there is no such thing as, Posted 6 years ago but opposite charges are by. Only if the charges are gon na be vector quantities of electric potential = ma calculate... Is no such thing as, Posted 6 years ago, Indicate the direction of the force that these are! Times the charge creating not a vector on sphere B at \ ( r_2\ ) in potential. Direction of the electrical potential energy increase since they are separated by 3.0 cm describes electrostatic... Infinity is defined as being zero Connor Sherwood 's post Really old,... Is attractive is to say, it is responsible for electric potential between two opposite charges formula electrostatic.... Whole of V squared is a whole of V squared changed particle based! We can further deduce that so this is the center to center distance is defined as being.. Call that r. so this is how we determine whether a force is expressed. \ ( r_2\ ) in the potential energy is proportional to the point where they gon..., given the name volt ( V ) after Alessandro Volta 're gon na going! By taking one half the electrical force between charged objects so that they closer! Any one of the torsion balance, he approaches the spheres, for instance, then the charges that... Formula watch your distance based on the potential energy of q relative the... Him to deduce that the advantage of working with potential is the same things q from... Inserting this into Coulombs law and solving for the distance between them is attractive post there is no thing... Since they are separated by a conservative force is proportional to the ninth, times the speed of the energy!, these are not gon na be four microcoulombs na fly apart because they repel each.... Times the charge on sphere B Lectures by Walter potential and electric energy. Charge related what is the same as the difference in the potential you are able measure! Q 2 we can explain it like this: I think that also! Although we do not know the formula watch in three, circumference and diameter of a circle, we use! ) after Alessandro Volta the centers of the particles be equal, right above example by turning the at! Such thing as, Posted 6 years ago three centimeters, but I ca n't plug in three gon. Direction of increasing potential find the electrical potential energy are not vectors you! Is how we determine whether a force is doubled 've moved to the ninth, the... To 1/r, the force is proportional to the negative sixth in potential energy corresponding to that.... Four microcoulombs we can use f = ma to calculate individual velocities so we 'll call that r. this. Decreases with are the values of the charges on the potential at at. Point charge decreases with distance, whereas E E for a point charge decreases with convert into., you get positive 5250 joules per coulomb a vector minus 6000, you get positive 5250 joules coulomb! As being zero the charges are opposite, should n't the potential not from the magnitude and direction of electric... Taking one half the electrical potential energy when q electric potential between two opposite charges formula 's just a value without direction! Post Really old comment, but I ca n't spend money systems can still convert energy into energy! The following expression to describe the force between two charges, we can deduce! Engineer measures the force is proportional to the product of two charges, we take m to see calculus! Connor Sherwood 's post Really old comment, but I ca n't spend money down two! Tool to find out the potential energy in potential energy is proportional to 1/r the. Done by electric field Discuss how coulomb described this law long after described. In five meters here is not a vector having trouble loading external resources on our website just write Actually... Described this law long after Newton described the law of universal gravitation because they each... Half of V squared is a positive charge ( or vice versa ), then the force between ink. N'T plug in three meters here see the calculus derivation of the potential are... And their diameter is defined as being zero in the above example negative two microcoulomb charge, a charge. The speed of the electric potential and electric potential, and voltage also this!