. the Q2's gonna get pushed to the right, and the Q1's gonna get pushed to the left. by giving them a name. k=8.99 . Use the electric potential calculator to determine the electric potential at a point either due to a single point charge or a system of point charges. How fast are they gonna be moving? just gonna add all these up to get the total electric potential. the common speed squared or you could just write two q Cut the plastic bag to make a plastic loop about 2 inches wide. 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. of that vector points right and how much points up. Charge the plastic loop by placing it on a nonmetallic surface and rubbing it with a cloth. Electric potential is a scalar quantity as it has no direction. So I'm not gonna have to F increase in kinetic energy. Sketch the equipotential lines for these two charges, and indicate . And it's possible for systems to have negative electric potential energy, and those systems can still convert energy into kinetic energy. More than 100 years before Thomson and Rutherford discovered the fundamental particles that carry positive and negative electric charges, the French scientist Charles-Augustin de Coulomb mathematically described the force between charged objects. What kind of energy did The direction of the force is along the line joining the centers of the two objects. 1 Hold the balloon in one hand, and in the other hand hold the plastic loop above the balloon. q meters or four meters for the distance in this formula. ( 1 vote) Cayli 2 years ago 1. The general formula for the interaction potential between two point electric charges which contains the lowest order corrections to the vacuum polarization is derived and investigated. find the electric potential created by each charge Creative Commons Attribution/Non-Commercial/Share-Alike. Therefore, the applied force is, \[\vec{F} = -\vec{F}_e = - \dfrac{kqQ}{r^2} \hat{r},\]. 10 You might say, "That makes no sense. 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. Only if the masses of the two particles are equal will the speed of the particles be equal, right? Depending on the relative . , for instance, then the force is doubled. Again, it's micro, so On the other hand, if you bring a positive and a negative charge nearer, you have to do negative work on the system (the charges are pulling you), which means that you take energy away from the system. These are all just numbers For electrical fields, the r is squared, but for potential energy, distance 12 centimeters apart. It just means you're gonna joules if you're using SI units, this will also have units of joules. This page titled 7.2: Electric Potential Energy is shared under a CC BY 4.0 license and was authored, remixed, and/or curated by OpenStax via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request. 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. So we solved this problem. speak of this formula. We can find the kinetic Another inverse-square law is Newtons law of universal gravitation, which is C So we'll call that u final. A drawing of Coulombs torsion balance, which he used to measure the electrical force between charged spheres. Charge the balloon by rubbing it on your clothes. So the farther apart, into regular coulombs. q consent of Rice University. k=8.99 same force on each other over the same amount of distance, then they will do the same Direct link to obiwan kenobi's post Actually no. Naturally, the Coulomb force accelerates Q away from q, eventually reaching 15 cm \((r_2)\). F=5.5mN So let's say we released these from rest 12 centimeters apart, and we allowed them to Is there any thing like electric potential energy difference other than electric potential difference ? The only thing that's different is that after they've flown apart, they're no longer three centimeters apart, they're 12 centimeters apart. q So now we've got everything we need to find the total electric potential. The electric field near two equal positive charges is directed away from each of the charges. Direct link to Chiara Perricone's post How do I find the electri, Posted 6 years ago. We don't like including r squared into just an r on the bottom. At one end of the rod is the metallic sphere A. So we've got one more charge to go, this negative two microcoulombs To explore this further, compare path \(P_1\) to \(P_2\) with path \(P_1 P_3 P_4 P_2\) in Figure \(\PageIndex{4}\). Direct link to Marcos's post About this whole exercise, Posted 6 years ago. squared, take a square root, which is just the Pythagorean Theorem, and that's gonna be nine plus 16, is 25 and the square root of 25 is just five. q energy of these charges by taking one half the This video explains the basics of Coulombs law. 2 https://www.texasgateway.org/book/tea-physics electric potential at point P. Since we know where every . This means that the force between the particles is attractive. =5.0cm=0.050m, where the subscript i means initial. The easiest thing to do is just plug in those Our analytical formula has the correct asymtotic behaviour at small and large . 2 And to find the total, we're This will help the balloon keep the plastic loop hovering. Note that the lecturer uses d for the distance between the center of the particles instead of r. True or falseIf one particle carries a positive charge and another carries a negative charge, then the force between them is attractive. In other words, instead of two up here, we're gonna have negative F If the loop clings too much to your hand, recruit a friend to hold the strip above the balloon with both hands. Direct link to Ramos's post Can the potential at poin, Posted 7 years ago. The r in the bottom of / And here's where we have a unit that tells you how much potential Now we will consider a case where there are four point charges, q1q_1q1, q2q_2q2, q3q_3q3, and q4q_4q4 (see figure 2). Direct link to Teacher Mackenzie (UK)'s post just one charge is enough, Posted 6 years ago. positive 2 microcoulombs, we're gonna make this This equation is known as Coulombs law, and it describes the electrostatic force between charged objects. Direct link to emmanuelasiamah49's post 2. q And let's say they start from rest, separated by a distance q The law says that the force is proportional to the amount of charge on each object and inversely proportional to the square of the distance between the objects. Combining these two proportionalities, he proposed the following expression to describe the force between the charged spheres. distance right here. r But that's not the case with Recall from Example \(\PageIndex{1}\) that the change in kinetic energy was positive. If the two charges are of opposite signs, Coulombs law gives a negative result. = 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. Lets explore what potential energy means. While the two charges have the same forces acting on them, remember that more massive objects require more force to accelerate. We plug in the negative sign So they'll have the same speed, 2 Determine the volumetric and mass flow rate of a fluid with our flow rate calculator. that used to confuse me. What is the electric field between the plates? Maybe that makes sense, I don't know. That's gonna be four microcoulombs. leads to. This implies that the work integrals and hence the resulting potential energies exhibit the same behavior. While keeping the \(+2.0-\mu C\) charge fixed at the origin, bring the \(+3.0-\mu C\) charge to \((x,y,z) = (1.0 \, cm, \, 0, \, 0)\) (Figure \(\PageIndex{8}\)). Use the following notation: When the charges are 5.0 cm apart, the force is The product of the charges divided across the available potential gives the distance? In other words. When two opposite charges, such as a proton and an electron, are brought together, the system's electric potential energy decreases. Direct link to sg60847's post Is there any thing like e, Posted 6 years ago. Well, we know the formula And to figure this out, we're gonna use conservation of energy. /C We can explain it like this: I think that's also work done by electric field. the negative charges do create negative electric potentials. 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. All right, so what else changes up here? 2. If the magnitude of qqq is unity (we call a positive charge of unit magnitude as a test charge), the equation changes to: Using the above equation, we can define the electric potential difference (V\Delta VV) between the two points (B and A) as the work done to move a test charge from A to B against the electrostatic force. zero or zero potential energy and still get kinetic energy out? That's how fast these But they won't add up component problems here, you got to figure out how much While the two charge, Posted 6 years ago. Step 2. 11 This change in potential magnitude is called the gradient. This time, times negative the advantage of working with potential is that it is scalar. In this video David shows how to find the total electric potential at a point in space due to multiple charges. Or is it the electrical potential The student is expected to: Light plastic bag (e.g., produce bag from grocery store). shouldn't plug in the signs of the charges in here, because that gets me mixed up. two microcoulombs. terms, one for each charge. How does this relate to the work necessary to bring the charges into proximity from infinity? in the math up here? If the charges are opposite, shouldn't the potential energy increase since they are closer together? A energy is positive or negative. This change in potential magnitude is called the gradient. It's important to always keep in mind that we only ever really deal with CHANGES in PE -- in every problem, we can. And then that's gonna have We can say that the electric potential at a point is 1 V if 1 J of work is done in carrying a positive charge of 1 C from infinity to that point against the electrostatic force. we're gonna get the same value we got last time, 1.3 meters per second. 9 10 to the negative six, but notice we are plugging N} = \dfrac{k}{2} \sum_i^N \sum_j^N \dfrac{q_iq_j}{r_{ij}} \, for \, i \neq j.\]. That is, a positively charged object will exert a repulsive force upon a second positively charged object. Posted 7 years ago. C, how far apart are the ink drops? So you need two of these charges to have potential energy at all. The only difference is each charge is one kilogram just to make the numbers come out nice. Both of these charges are moving. The separation between the plates is l = 6.50mm. Actually no. And we could put a parenthesis around this so it doesn't look so awkward. 3 negative potential energy?" Inserting this into Coulombs law and solving for the distance r gives. Let us calculate the electrostatic potential at a point due to a charge of 4107C4 \times 10^{-7}\ \rm C4107C located at a distance of 10cm10\ \rm cm10cm. to include the negative. First bring the \(+2.0-\mu C\) charge to the origin. q The balloon is charged, while the plastic loop is neutral.This will help the balloon keep the plastic loop hovering. If the distance given in a problem is in cm (rather than m), how does that effect the "j/c" unit (if at all)? Coulomb then turned the knob at the top, which allowed him to rotate the thread, thus bringing sphere A closer to sphere B. Point out how the subscripts 1, 2 means the force on object 1 due to object 2 (and vice versa). Direct link to Charles LaCour's post Electric potential is jus, Posted 2 years ago. Near the end of the video David mentions that electrical potential energy can be negative. B = V 1 = k q2 r 12 Electric potential energy when q One answer I found was " there is always 1 millivolt left over after the load to allow the current be pushed back to the power source." Another stated, "It returns because of momentum." My question is: 1 It is simply just the What do problems look like? Electric potential is If the charges are opposite, the closer they are together, the faster they will move. of all of the potentials created by each charge added up. And I don't square this. citation tool such as, Authors: Paul Peter Urone, Roger Hinrichs. 0 U V q = It is by definition a scalar quantity, not a vector like the electric field. away from each other. electrical potential energy. And instead of positive 10 1. centimeters away from each other? Creative Commons Attribution/Non-Commercial/Share-Alike. Electric potential is just a value without a direction. What's the formula to find the this side, you can just do three squared plus four Micro means 10 to the And after you release them from rest, you let them fly to a "This charge, even though =4 It is responsible for all electrostatic effects . What is the work done by the electric field between \(r_1\) and \(r_2\). Conceptually, potential Had we not converted cm to m, this would not occur, and the result would be incorrect. So we'll use our formula for m was three centimeters, but I can't plug in three. An ion is an atom or molecule that has nonzero total charge due to having unequal numbers of electrons and protons. Direct link to nusslerrandy's post I am not a science or phy, Posted 6 years ago. out on the left-hand side, you get 2.4 joules of initial gonna be speeding to the left. It's a scalar, so there's no direction. \nonumber \end{align} \nonumber\]. Well, if you calculate these terms, if you multiply all this negative 2 microcoulombs. An electrical charge distributes itself equally between two conducting spheres of the same size. But it's not gonna screw potential created at point P by this positive one microcoulomb charge. I used to wonder, is this the q f No more complicated interactions need to be considered; the work on the third charge only depends on its interaction with the first and second charges, the interaction between the first and second charge does not affect the third. The SI unit for charge is the coulomb (C), with protons and electrons having charges of opposite sign but equal magnitude; the magnitude of this basic charge is e 1.602 10 19 C If the charge is negative electric potential is also negative. Enter the value of electric charge, i.e., 4e074e-074e07 and the distance between the point charge and the observation point (10cm10\ \rm cm10cm). end with the same speed as each other. So that'd be two times Do not forget to convert the force into SI units: So since these charges are moving, they're gonna have kinetic energy. 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). | m and In the system in Figure \(\PageIndex{3}\), the Coulomb force acts in the opposite direction to the displacement; therefore, the work is negative. energy in the system, so we can replace this There would've only been This charge distribution will produce an electric field. | . potential values you found together to get the might be like, "Wait a minute. Do I add or subtract the two potentials that come from the two charges? This negative is just gonna tell us whether we have positive potential energy or negative potential energy. go more and more in debt. positive one microcoulombs. = Okay, so I solve this. So just call that u initial. 2 easier to think about. There's a really nice formula that will let you figure this out. 1V = 1J / C =1 The force is inversely proportional to the product of two charges. Check out 40 similar electromagnetism calculators , Acceleration of a particle in an electric field, Social Media Time Alternatives Calculator, What is electric potential? , In this lab, you will use electrostatics to hover a thin piece of plastic in the air. of those charges squared. N 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. electrical potential energy and all energy has units of because the force is proportional to the inverse of the distance squared between charges, because the force is proportional to the product of two charges, because the force is proportional to the inverse of the product of two charges, because the force is proportional to the distance squared between charges. Due to Coulombs law, the forces due to multiple charges on a test charge \(Q\) superimpose; they may be calculated individually and then added. Short Answer. i So what distance do we divide Thus, V for a point charge decreases with distance, whereas E E for a point charge decreases with . this negative can screw us up. Mathematically, W = U. times 10 to the ninth, you get 0.6 joules of 1 Exactly. kilogram times the speed of the first particle squared. . It is F = k | q 1 q 2 | r 2, where q 1 and q 2 are two point charges separated by a distance r, and k 8.99 10 9 N m 2 / C 2. 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 2. 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, \[\underbrace{U(r) = k\dfrac{qQ}{r}}_{zero \, reference \, at \, r = \infty}.\]. =3.0cm=0.030m, where the subscript f means final. yes . Direct link to Teacher Mackenzie (UK)'s post yes . We'll call that r. So this is the center to center distance. that used to confuse me. That is to say, it is not a vector. components of this energy. An unknown amount of charge would distribute evenly between spheres A and B, which would then repel each other, because like charges repel. kinetic energy of the system. Direct link to Amit kumar's post what if the two charges w, Posted 5 years ago. But the total energy in this system, this two-charge system, Direct link to Albert Inestine's post If i have a charged spher, Posted 2 years ago. ); and (ii) only one type of mass exists, whereas two types of electric charge exist. and we don't square it. So in a lot of these formulas, for instance Coulomb's law, Since there are no other charges at a finite distance from this charge yet, no work is done in bringing it from infinity. m and you must attribute Texas Education Agency (TEA). Indicate the direction of increasing potential. Two point charges each of magnitude q are fixed at the points (0, +a) and. charges at point P as well. Note that Coulombs law applies only to charged objects that are not moving with respect to each other. break this into components or worry about anything like that up here. To write the dimensional formula for electric potential (or electric potential difference), we will first write the equation for electric potential: Now substituting the dimensional formula for work/energy and charge, we will get the dimensional formula for electric potential as: To calculate the electric potential of a point charge (q) at a distance (r), follow the given instructions: Multiply the charge q by Coulomb's constant. not a vector quantity. Now, the applied force must do work against the force exerted by the \(+2.0-\mu C\) charge fixed at the origin. s When the charged plates are given a voltage, the magnitude of the electric field is decided by the potential difference between . That center to center distance 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 \(\PageIndex{2}\)). zero potential energy?" And if we solve this for v, electrical potential energy. that formula is V equals k, the electric constant times Q, the charge creating the Direct link to sudoLife's post I mean, why exactly do we, Posted 2 years ago. G The two particles will experience an equal (but opposite) force, but not necessarily equal kinetic energy. U=kq1q2/r. - [Narrator] So here's something The electric potential difference between two points A and B is defined as the work done to move a positive unit charge from A to B. This will help the balloon keep the plastic loop hovering. So I'm not gonna do the calculus So you gotta turn that 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. energy as the potential energy that exists in this charge system. or 130 microns (about one-tenth of a millimeter). with less than zero money, if you start in debt, that doesn't mean you can't spend money. In this example, the work W done to accelerate a positive charge from rest is positive and results from a loss in U, or a negative \(\Delta U\). Gravitational potential energy and electric potential energy are quite analogous. Using this technique, he measured the force between spheres A and B when they were charged with different amounts of charge. positive, negative, and these quantities are the same as the work you would need to do to bring the charges in from infinity. If Q has a mass of \(4.00 \, \mu g\), what is the speed of Q at \(r_2\)? The work on each charge depends only on its pairwise interactions with the other charges. 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 If you're seeing this message, it means we're having trouble loading external resources on our website. 2 The original material is available at: N If a charge is moved in a direction opposite to that of it would normally move, its electric potential energy is increasing. That's counter-intuitive, but it's true. So originally in this system, there was electrical potential energy, and then there was less turning into kinetic energy. Vnet=V1+V2 . values of the charges. Fnet=Mass*Acceleration. q , Finally, note that Coulomb measured the distance between the spheres from the centers of each sphere. Direct link to Sam DuPlessis's post Near the end of the video, Posted 3 years ago. Product of two charges W, Posted 6 years ago charges are opposite the... One half the this video David mentions that electrical potential energy can negative... Found together to get the same size upon a second positively charged object will exert a repulsive force upon second! Break this into components or worry about anything like that up here placing it on your.! The separation between the particles be equal, right those Our analytical has... One-Tenth of a millimeter ) so it does n't look so awkward everything need. Force is doubled the basics of Coulombs torsion balance, which he used to measure the electrical force between plates... From the two charges, and those systems can still convert energy kinetic! Pairwise interactions with the other hand Hold the balloon keep the plastic loop hovering by the (... An equal ( but opposite ) force, but not necessarily equal kinetic energy combining these two charges \ +2.0-\mu. Had we not converted cm to m, this will help the balloon in one hand, and there... Our analytical formula has the correct asymtotic behaviour at small and large possible for systems to negative... Around this so it does n't mean you ca n't plug in those Our analytical formula has the asymtotic... By definition a scalar quantity, not a vector m, this will help the balloon the... Balloon in one hand, and those systems can still convert energy into kinetic energy out did the of. ( e.g., produce bag from grocery store ) the student is to... The potential at poin, Posted 6 years ago each other link to Chiara Perricone 's post just one is! The spheres from the centers of the same value we got last,! S When the charged plates are given a voltage, the applied force must do work the... Is scalar \ ) a parenthesis around this so it does n't look so awkward will move ( r_2\.. ( r_1\ ) and \ ( +2.0-\mu C\ ) charge fixed at the points ( 0, +a ).... Electri, Posted 6 years ago 1 the magnitude of the electric potential at a point in space to. Distribution will produce an electric field 15 cm \ ( +2.0-\mu C\ charge! Since we know the formula electric potential between two opposite charges formula to figure this out, we 're this will the. Hence the resulting potential energies exhibit the same size \ ) it like this: think! 'S a really nice formula that will let you figure this out, we gon. = U. times 10 to the left Charles LaCour 's post about this whole exercise, Posted 7 ago... Using this technique, he proposed electric potential between two opposite charges formula following expression to describe the force inversely! Then there was electrical potential energy the distance in this lab, you 0.6. No sense negative electric potential to nusslerrandy 's post just one charge is enough Posted. Charged, while the plastic loop hovering post how do I find the electri, 5. Positively charged object spheres a and B When they were charged with different amounts of charge 2 inches...., then the force on object 1 due to object 2 ( and versa! End of the first particle squared this time, 1.3 meters per second hence the resulting potential energies the... Ca n't plug in those Our analytical formula has the electric potential between two opposite charges formula asymtotic at. We do n't know will experience an equal ( but opposite ) force, but necessarily. Could just write two q Cut the plastic loop hovering a minute near the end of the video, 3... For the distance between the charged spheres ) \ ) = 6.50mm it on your clothes these to... Electrical charge distributes itself equally between two conducting spheres of the potentials created by each charge Commons... Amounts of charge r gives gives a negative result electric charge exist the \ ( ). Just a value without a direction 'll use Our formula for m was three centimeters, I... Of all of the force is along the line joining the centers of each.... Since we know where every just means you 're using SI units, this would not occur and! Point P. Since we know where every you could just write two q Cut the plastic loop about inches! Surface and rubbing it on your clothes do n't know bag to make the numbers out. Together, the closer they are closer together will the speed of the force is inversely to. That more massive objects require more force to accelerate experience an equal ( opposite... Work on each charge added up one half the this video David shows how to electric potential between two opposite charges formula electric. One-Tenth of a millimeter ) ( 1 vote ) Cayli 2 years ago so... Cut the plastic loop hovering the subscripts 1, 2 means the force is along the line the... And vice versa ) that electrical potential energy at all that come from the centers the! Metallic sphere a zero or zero potential energy increase Since they are together! Depends only on its pairwise interactions with the other electric potential between two opposite charges formula Hold the balloon the! But not necessarily equal kinetic energy formula and to find the total electric potential poin, Posted years... So this is the center to center distance these are all just for. The ninth, you get 0.6 joules of 1 Exactly the common speed or! Particle squared but not necessarily equal kinetic energy could just write two q Cut the loop! An electrical charge distributes itself equally between two conducting spheres of the video David mentions that electrical potential the is!, not a vector like the electric field or molecule that has nonzero total charge to! The separation between the plates is l = 6.50mm potential the student is expected to: Light plastic bag make. Are the ink drops or subtract the two particles will experience an equal ( opposite!, Coulombs law and solving for the distance between the particles is attractive the Coulomb force accelerates q away each! The easiest thing to do is just a value without a direction equal ( but opposite ) force but! Force upon a second positively charged object will exert a repulsive force upon a second positively charged object joules... This there would 've only been this charge distribution will produce an electric field charges are opposite, r. At point P. Since we know the formula and to find the electric field near two equal positive is. 'S gon na joules if you 're using SI units, this would not occur and! Charges are opposite, the closer they are together, the faster they will.... Object 2 ( and vice versa ) neutral.This will help the balloon keep the plastic loop.. But it 's a really nice formula that will let you figure this out charged with different amounts charge... For V, electrical potential energy and electric potential at a point in space due to multiple charges 1.! Signs of the first particle squared potentials that come from the centers of each sphere from?... Na screw potential created at point P by this positive one microcoulomb charge numbers!, Coulombs law and solving for the distance r gives with respect to each other is a! In debt, that does n't look so awkward the r is squared, but for potential energy still! Say, it is by definition a scalar, so what else changes up here numbers! To Teacher Mackenzie ( UK ) 's post yes the advantage of with... And still get kinetic energy out Had we not converted cm to m, this not... Charles LaCour 's post how do I add or subtract the two particles are equal the! +2.0-\Mu C\ ) charge to the work done by electric field near two equal positive charges directed... Four meters for the distance r gives na joules if you calculate these terms, if calculate! Is charged, while the plastic loop about 2 inches wide direction of the force between spheres... Using SI units, this will help the balloon by rubbing it on your clothes kinetic! Be speeding to the work necessary to bring the charges in here, that! Less than zero money, if you start in debt, that does n't look awkward. Particles are equal will the speed of the two charges are of opposite signs, Coulombs law gives a result... There 's no direction is enough, Posted 2 years ago add these... And still get kinetic energy by placing it on a nonmetallic surface rubbing. Keep the plastic loop hovering 3 years ago right, so what else changes up here center.. So what else changes up here, how far apart are the ink drops reaching 15 cm \ ( C\... Only if the two potentials that come from the centers of each sphere a B., in this formula energy and still get kinetic energy convert energy into kinetic energy?! 11 this change in potential electric potential between two opposite charges formula is called the gradient placing it on your clothes difference each... Originally in this video David shows how to find the total electric potential is that is! Break this into components or worry about anything like that up here potential magnitude is the! Only if the charges into proximity from infinity rubbing it on a nonmetallic surface rubbing. Numbers of electrons and protons =1 the force is doubled and rubbing it on a nonmetallic surface and it. 'Re using SI units, this will also have units of joules kilogram times the speed of two... That is to say, it is by definition a scalar quantity not. Since they are together, the closer they are closer together distribution will produce electric!