Electric potential energy Definition and 182 Threads

Homework Statement A solid sphere of radius R has a uniform charge density ρ and total charge Q. Derive an expression for its total electric potential energy. Suggestion: Imagine that the sphere is constructed by adding successive layers of concentric shells of charge dq = (4\pi r^{2} dr) ρ...

I'm currently reading on my own on these topics for the first time in Fundamentals of Physics by HRW. Electric charge, electric fields, and Gauss' Law were 3 hard chapters, but manageable. In this chapter certain aspects aren't really clear to me at all, and there is more math than physical...

Homework Statement "Two point charges 2.0cm apart have an electric potential energy -180 microJoules. The total charge is 31 nC. What are the two charges?" Homework Equations V= k * q / r The Attempt at a Solution I understand that V = -180 * 10^-6, k = 9*10^9, r = 0.02m, and the...

Homework Statement Are Electric potential and Electrical Potential Energy same or different? Homework Equations The Attempt at a Solution Electric Potential at a point is defined as the amount of work done in moving a unit positive charge from infinity to that point against the...

Hi, I've been thinking on this for a while, any help would be great :) I have a box placed over a table. There's a pen kept over the box. What I do here is move the pen slowly, without changing its velocity and bring it down on the table. Assuming the table and box are at a height h1...

Homework Statement \ Hi there! We are currently studying forces and fields in physics and we are in the electrostatics chapter. I am having a bit of trouble fully understanding electric potential energy. The book states that electric potential energy is defined as the work required to move a...

Hey friends, I am stuck up in the derivation of the electric potential energy due to a charge 'Q' at the origin on test charge 'q' at a point p (position vector 'rp'). The derivation is shown below, am just struggling with a minus sign... Electric Potential Energy at P = Work done to move...

Homework Statement There's no problem per se, I'm just confused by the definition of work and electric potential energy: work done by the electric field is defined to be the negative of delta_U, the change in electric potential energy. This definition makes sense to me. However, according...

Hello. This is my first post! Thanks in advance for any help given. Homework Statement A constant electric field is in the positive X direction as shown in the diagram below. Also shown are two paths through which a charge can move from point A to point C. In the first path path the...

Homework Statement It is actually not a problem, but a formulation of the electric potential energy in a dielectric medium present in a book, which seems to me as inconsistent with the way it is usually defined in electromagnetism books. I can't see it as a typo or a mistake because the author...

1. Is it possible to caculate the electric potential energy and the gravitational potential energy between two nucleon of deuterium (1 proton, 1 neutron), if we know the binding energy of deuterium is 2.23 (MeV), and the distance between them is 1 (fm)? Please help me! I'm really confused about...

Homework Statement It's a problem on Halliday's Fundamentals of Physics's 24th chapter. This problem gives us N-electrons on a circle with radius R. The electrons are placed on the same distances so these electron positioning has a circular symmetry. And it also gives us another...

Two protons are a distance 610–9 m apart. What is the electric potential energy of the system consisting of the two protons? Uelec = (1/4piepsilonnot)*q1q2/r where (1/4piepsilonnot) = 9x10^9 n*m/coulomb^2 The mass of the proton is 1.7*10^-27 for my answer i got 4.335e-36 but...

A Particle of charge q=7.5x10^-6 Coulombs is released from rest at .6m on the x axis. The particle moves due to charge Q = -20x10-6 C. What is the Kinetic Energy of the particle the instant it has moved .4 meters if Q stays fixed at the origin? Here I used KE1 + U1 = KE2 + U2 Which equals 0 +...

Two metal spheres are connected by a long wire with a switch. The radius of the larger sphere (B) is b= 0.20 m and the radius of the smaller sphere (A) is a= 0.080 m. Initially the switch is open and both spheres have zero charge. Then charge Q0 = 1.0 μC is placed on the larger sphere. B)...

A sphere of radius r contains a charge Q distributed uniformly throughout its volume. Charge dQ is brought in from infinity and deposited uniformly over the surface. The potential energy of the charge dQ is Q dQ/4\pi\epsilon0. This follows naturally from the result for the potential of 2 point...

Homework Statement A charge of –4.00 µC is fixed in place. From a horizontal distance of 55.0 cm, a particle of mass 2.50 × 10–3 kg and charge –3.00 µC is fired with an initial speed of 15.0 m/s directly toward the fixed charge. How far does the particle travel before it stops and begins to...

Homework Statement Three equal point charges, each with charge 1.95 nanoC , are placed at the vertices of an equilateral triangle whose sides are of length 0.550m . What is the electric potential energy of the system? (Take as zero the potential energy of the three charges when they are...

Electric Potential Energy Among Multiple Charges kinda aurgent [b]1. Homework Statement Four point charges, fixed in place, form a square with side length d. (See image) http://i23.photobucket.com/albums/b354/h4llw4x0r/notSoFast.jpg The particle with charge q is now released and given...

how would you solve this problem? A charge q1 = 3.40 nC is placed at the origin. Three identical charges, q2, q3 q4, are placed at the positions (0.100 m, 0 m), (0 m, 0.100 m), and (0.100 m, 0.100 m). What is the potential energy of this configuration of charges? should you do answer =...

Homework Statement Two small metal spheres, each of mass m, are attached to the lower ends of two long insulated strings of negligible mass as shown. Each string is length, l. The spheres are pulled apart until each string makes an angle "theta" with the horizontal. A charge of +q is placed...

A charged particle (either proton or electron) is moving rightward between 2 parallel charged plates separated by distance d = 2mm. The plate potentials are V1 = -70.0 V and V2 = -50.0 V. The particle is slowing from an initial speed of 90.0 km/s at the left plate. a) Is the particle an electron...

Two insulating spheres have radii 0.3cm and 0.5cm, masses 0.1kg and 0.7kg and uniformly distributed charges of -2 \muC and 3 \muC. they are released when the distance from their center are 1m apart. How fast will each be moving when they collide. Firstly, what is the radius of the sphere use...

I'm having a little bit of trouble understanding the concept that the potential electrical energy between two opposite charges is negative while between like charges it is positive. Can someone please explain in detail why this is so? Thanks in advance.

Homework Statement A square of side a has a charge +Q at each corner. What is the electric potential energy of this system of charges? Express your answer in terms of the variables a, Q and appropriate constants. Homework Equations U=kq1q2/r The Attempt at a Solution I figured...

Homework Statement In proton-beam therapy, a high-energy beam of protons is fired at a tumor. The protons come to rest in the tumor, depositing their kinetic energy and breaking apart the tumor’s DNA, thus killing its cells. For one patient, it is desired that 0.10 J of proton energy be...

1. Calculate the change in electric potential energy for a -10µC charge in a uniform electric field of strength 1750 N/C, traveling in a the straight paths OA, OB, or OC as shown. The figure shown is a rectangle with OA being a base, OC being a side and OB being a diagonal (No angle is given)...

Four charges are arranged at the corners of a rectangle as shown in the diagram. How much work needs to be done to move the charge q2 to infinity? Since change in PEe = W, am I suppose to find total potential electric energy of the four charges and then subtract the total potential electric...

Homework Statement There is a thin rod of length L that carries a uniform charge per unit length \lambda. Starting from the expression for the potential of a point charge, derive an expression for the electric potential V (y) at a distance y away from the centre of the rod on the axis (y) of...

[b]1. The problem statement, all variables and given/known For a a uniformly charged sphere of radius R with total charge Q, show that the potential energy of a point charge q' varies with r U(r) = Qq'/4\pi\epsilonR * (3/2 - r2/2R2 if r < R Homework Equations \DeltaU = - \intE(r)q'dr...

1. Homework Statement A tire of radius 32.5 cm has a surface that is conducting. A charge of 4.89×10-8 C is then placed on the surface. The potential on the tire's surface is 1.35E+03 V. Later, suppose that some of the air is let out of the tire, so that the radius shrinks to 10.5 cm, the new...

Homework Statement A tire of radius 32.5 cm has a surface that is conducting. A charge of 4.89×10-8 C is then placed on the surface. The potential on the balloon's surface is 1.35E+03 V. Later, suppose that some of the air is let out of the tire, so that the radius shrinks to 10.5 cm, the...

Homework Statement A uniform electric field with a magnitude of 6890 N/C points in the positive x-direction. Find the change in electric potential energy when a +12.5 µC charge is moved 5.87 cm in the following directions. In the positive x-direction In the negative x-direction...

Homework Statement A point charge q_1 = 86.5 uC is held fixed at the origin. A second point charge, with mass m = 5.90×10−2 kg and charge q2 = -2.95 uC, is placed at the location (0.323 m, 0) 1) Find the electric potential energy of this system of charges. 2)If the second charge is released...

1. During a particular thunderstorm, the electric potential difference between the clouds and the ground is Vcloud-Vground = 10^9 Volts with the cloud being at the higher potential. Now, there is a lightning flash in which a charge of -25C is transferred from the groud to the cloud. 2. a)...

Homework Statement From Young and Freedman's book University Physics, ch 23, problem 23.54: In the Bohr model of the hydrogen atom, a single electron revolves around a single proton in a circle of radius r. Assume the proton remains at rest. ++ (the rest is irrelevant to my question)...

Homework Statement Two point charges , Qz= +5.00 nanoC and Q2= -3.00 nanoC, are separated by 35.00 cm. a) What is the potential energy of the pair? What is the significance of the algebraic sign? b) what is electrical potential at a point midway between the charges? (here I'm supposing i'd...

A test charge of +1.0 x 10^-6 C is 40 cm from a charged sphere of 3.2 x 10^-3 C. a) How much work was required to move it there from a point 1.0 x 10^2 m away from the sphere? b) How many electrons were gained or lost from the test object. Relevant equations: Ee = kq1q2/r N = q/E...

I recently found out how to calculate the potential energy of a charged insulated sphere of radius R and charge density rho. I would like to know how to calculate the potential energy for other geometric objects, such as a line of charges, a sheet of charges, or a pyramid of charges. I don't...

I've done an exercise that made me think a bit. Here's it is : https://www.physicsforums.com/showthread.php?t=333608. So the electric potential energy of a 1 dimensional crystal (lattice?) formed by alternating ions is about \frac{-ke^2 \ln 2}{a}. So as it is a negative number, I would have...

Homework Statement There were two parts to this problem a) if you do 12 J of work to push 0.001 C of charge from point A to point B in an electric field, what is the voltage difference between A and B? I already solved this part, I got \DeltaV=12,000 V b) When the charge is...

Homework Statement I've just come across a lot of concept questions about electric potential energy and electric potential, and I can't differentiate between the two really. I know electric potential is also called voltage. Here's one question for example: How can electric potential be...

Homework Statement A, B, C and D are corners of a square in empty space, sides 12 micrometres, charges +5nC and -5nC are placed at corners A and B respectively. What is the change in the electric potential from D to C? (take care with sign) A third charge of -2nC is initially at D then...

Homework Statement Questions and solutions are given. However, I have some questions. 26.47. Can anyone explain to me in more detail this solution? For instance, why do they reverse the order and add them together (equations 2 and 3)? And how does one obtain this obvious Calculus...

Homework Statement A test charge of +1.0x10^-6 C is 40cm from a charged sphere of 3.2x10^-3 C. How much work was required to move it there from a point 1.0x10^2 m away from the sphere? Homework Equations W = \DeltaE W = Ee2 - Ee1 The Attempt at a Solution Ee2 =...

I just read this article (http://physics.bu.edu/~duffy/PY106/Potential.html). I am stuck on just one line where it says that potential energy is in negative...please read this and explain... """""An example : Ionization energy of the electron in a hydrogen atom In the Bohr model of a...

Homework Statement The Bohr model The Bohr model correctly predicts the main energy levels not only for atomic hydrogen but also for other "one-electron" atoms where all but one of the atomic electrons has been moved, as as in He+ (one electron removed) or Li++ (two electrons removed). To...

Homework Statement A proton and an alpha-particle are fired directly toward each other from far away each with an initial speed of 0.01c. Determine their distance of closest approach measured between their centres. Homework Equations See below.The Attempt at a Solution What I did was...

My book first introduces expressions for work and energy by referring to concepts from mechanics and gravitation. It uses the familiar expressions F =mg (-y direction) & U=mgy to explain the expressions it gives for electric potential energy. However... I understand that the force due to gravity...

all my question is listed in the file below thanks for your help