Electric potential Definition and 1000 Threads

Hi, I was wondering, if a circuit is open, would capacitors still have a potential difference ? If there is no potential difference, can we say its potential is 0 then obtain a charge equal to 0 for the capacitor's charge ?

Homework Statement [PLAIN]http://img203.imageshack.us/img203/5679/physics2h.png Homework Equations Included above I believe... The Attempt at a Solution a) i think dq=\lambda2\pidy Some of the calculus that we are using I am shaky on and I just don't understand what is being asked here...

Homework Statement (a) Calculate the speed of a proton that is accelerated from rest through an electric potential difference of 120V (b) Calculate the speed of an electron that is accelerated from rest through an electric potential difference of 120V The Attempt at a Solution...

Homework Statement I have a series of questions regarding electric potential at various points in space given various point charges. The one that would probably be best to focus on is a charge of +q and a second charge of -2q a distance "d" further along the x-axis, find the non-infinity...

Homework Statement Two point charges, -q and q/3, are situated at the origin and at the point (a,0,0) respectively. At what point on the x-axis does the Electric Field Vanish? Find the potential function and show that the V = 0 equipotential surface is a sphere Homework Equations...

Homework Statement Find an expression for the electric potential a distance z away from the center of a thin uniformly charged rod of length L on a line that bisects the rod. Homework Equations V=k\frac{Q}{r} The Attempt at a Solution Determine the electric potential due to one...

Hello, I'm working on a problem where I'm given V, the electric potential, and asked to find E, the electric field. So I took the partial derivatives and found Ex, Ey, Ez. But now I was wondering how to present this answer, since it is the components of the electric field and not the electric...

Homework Statement Particles A (of mass m and charge Q) and B (of m and charge 5 Q) are released from rest with the distance between them equal to 1.411 m. If Q = 25 µC, what is the kinetic energy of particle B at the instant when the particles are 3.411 m apart? Answer in units of J...

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 The work done by an external force on an electron as it moves from point A to point B is 6.3 × 10-14 J. If it was started from rest and had 3 × 10-14 J of kinetic energy when it reached B, what is the potential difference VB-VA? Homework Equations V = k (q/r) Delta V =...

In a certain region of space, the electric potential is given by V = y^2 + 5xy - 2xyz. Determine the x-, y-, and z-components of the electric field, E, at (5, 2, 3). Do not enter units. I took the partial derivatives with respect to each coordinate: Ex = -∂V/∂x = -[5y-2yz] = -5y+2yz Ey =...

Homework Statement Two point charges -2Q and +3Q are on the x-axis at the origin and at x = L. Find all the points on the x-axis (not at infinity) where the electric potential is zero. Express your answers in terms of L and Q.Homework Equations V= k*Q/rThe Attempt at a Solution I understand...

Homework Statement Two isolated, concentric, conducting spherical shells have radii R1 = 0.510 m and R2 = 1.10 m, uniform charges q1 = +1.90 μC and q2 = +2.50 μC, and negligible thicknesses. What is the magnitude of the electric field E at radial distance (a)r = 4.50 m, (b)r = 0.840 m, and...

Homework Statement Electric Potential from Electric Field Suppose that, as a function of x, y, and z, an electric field has the following components: Ex = 6x^2y, Ey = 2x^3 + 2y and Ez = 0 where E is measured in V/m and the distances are measured in m. Find the electrical potential...

Homework Statement A point charge q = -8 µC is surrounded by two thick, conducting spherical shells of inner and outer radii a1 = 0.3 m, a2 = 0.4 m, a3 = 0.7 m, and a4 = 0.8 m respectively. The inner shell is uncharged; the outer shell has a net charge Q = -10 µC. At this point in the problem...

Homework Statement A particular Gieger counter has a metal cylinder with an inner diameter of 1.9 cm along whose axis is stretched a wire with 24 N of tension. The potential difference between the wire and the cylinder is 870 volts. The wire has a length of 8 cm and an outer diameter of 1.1 X...

I was working on E&M I homework with my friend, and the final question was to find the electric potential at any point on the positive x-axis of a charged disk (where the x-axis is perpendicular to the centre of the disk) We solved this easily enough, starting with a point charge and...

Homework Statement A charge of +21.9 micro-Coulombs is placed at x=-3.3 m, y=0 m, a charge of -8.5 micro-Coulombs is placed at x=0 m, y=+3.8 m, and a charge of +15.6 micro-Coulombs is placed at x=+3.3 m, y=+3.8 m. If a charge of -15.4 micro-Coulombs is placed at origin, what is electrical...

Homework Statement Charges + and -q are placed at -1cm and 1cm along the y axis. If their electric potential energy is -45microJ, what is q? Homework Equations U=qV V=Es The Attempt at a Solution I got an equation for the electric potential between the two charges, but it was...

Homework Statement Much of the material making up Saturn's rings is in the form of tiny dust grains having radii on the order of 10^-6 these grains are located in a region containing a dilute ionized gas, and they pick up excess electrons. As an approximation suppose each grain is sphereical...

Homework Statement How much work is required to assemble eight identical point charges, each of magnitude q, at the corners of a cube of side s? Note: Assume a reference level of potential V = 0 at r = infinity. (Use any variable or symbol stated above along with the following as necessary...

Homework Statement An infinite, uniform line charge with linear charge density λ = +5 µC/m is placed along the symmetry axis (z-axis) of an infinite, thick conducting cylindrical shell of inner radius a = 3 cm and outer radius b = 4 cm. The cylindrical shell has zero net charge. The...

Homework Statement Two positive charges, each with Q = +12 µC, are fixed to the x-axis at x = +a and x = -a, where a = 2 m. Part A was not a poblem to find. (a) Find the electric potential at point A on the y-axis where (xA, yA) = (0, b) and b = 5 m. Take the zero of potential to be at...

Homework Statement A point charge q = -8 μC is surrounded by two thick, conducting spherical shells of inner and outer radii a1 = 0.3 m, a2 = 0.4 m, a3 = 0.7 m, and a4 = 0.8 m respectively. The inner shell is uncharged; the outer shell has a net charge Q = -10 μC. At this point in the...

Homework Statement Two equal point charges Q = 5.18 C are separated by a distance d = 2.00 m. (See figure.) http://homework.phyast.pitt.edu/res/msu/nagytibo/Electromagnetism/Electrostatics/graphics/010a.gif Point A is halfway between the charges and point B is located 1.00 m to the...

Why is the electric potential in the middle of two oppositely charged points 0? Does this also mean that there's no potential energy at this point?

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...

Hi, this is my first time posting on the forums, so if I make any mistakes, I'm sorry. Homework Statement This question has already been started here: https://www.physicsforums.com/showthread.php?t=449070 but they never got to part (b). PART A A -10.1 nC point charge and a +18.9 nC...

Homework Statement In the presence of a uniform electric field, E=-6.0 i + .8 j + 3.42 k N/C, assume that the electric potential is -5V at the origin of the coordinate system, and determine the electric potential at the point 2.7 i -2.7 k. Here's what I've done so far \DeltaV=V(2.7, 0...

Homework Statement Consider the following figure. image: http://www.webassign.net/grr/p17-18.gif" (a) Find the electric potential at points a and b for charges of +3.5 nC and -7.6 nC located as shown in the figure. Va= _____ V Vb= _____ V (b) What is the potential difference ΔV...

Homework Statement What electric potential difference is required to accelerate and electron, initially at rest, to the speed at which it will move in a circular path with radius 1cm when the electron enters a region of uniform magnetic field of 1.0T, if the field is perpendicular to the...

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 A proton with an intial speed of 800,000m/s is brought to rest by an electric field. What was the potential difference that stopped the proton.Homework Equations Ki + qvi = Kf + qvf k=.5mv^2 The Attempt at a Solution Voltage final = ? vi = 800,000m/s v2=0 q=1.60x10^-19...

Homework Statement See figure below, Homework Equations The Attempt at a Solution I'm not sure how to use the sigma factor in this question. I know that, W= Fd So, W = Eqd but I don't know how to get any farther. What am I missing? How do I take advantage...

Homework Statement A plutonium-239 nucleus, initially at rest, undergoes alpha decay to produce a uranium-235 nucleus. The uranium-235 nucleus has a mass of 3.90x10^-25 kg, & moves away from the location of the decay with a speed of 2.62x10^5 m/s. Determine the minum electric potential...

Homework Statement I'm working out of Griffith's "Intro to Electrodynamics" and the problem states: "A conical surface (an empty ice-cream cone) carries a surface charge \sigma. The height of the cone is h as is the radius of the top. Find the potential difference between points a (the...

Homework Statement You have a Square with 10cm lengths on each side. Charges of +4 microC (top right corner), -6 microC (top left corner), and +4 microC (bottom left corner) are located at three corners of the square. A) Calculate the electric field in the empty corner of the square. B)...

I hope I'm posting this in the right spot, but I've been wondering this for a while now and figured this would be the best place to ask... I know that rust is an process involving electricity and rust forms on the negatively charged anode right? If that's the case, since a car is on rubber...

Homework Statement Taken from Resnick and Halliday: A Geiger counter has a metal cylinder 2.10 cm in diameter along whose axis is stretched a wire 1.34E-4 cm in diameter. If 855 V is applied between them, find the electric field at the surface of (a) the wire and (b) the cylinder...

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 Consider a protein sphere with a radius of 18Å, and charge Q = -10e, in an aqueous solution of c = 0.05M NaCl at 25 ˚C. We consider the small ions as point charges and use the linear approximation to the Poisson-Boltzmann equation. What is the surface potential of the...

Homework Statement Find the electric potential difference at a point 4.0x10-2m away from an alpha particle. Homework Equations V= kq/r The Attempt at a Solution k= 9x109 r= 4.0x10-2 I'm not quite sure how to get this answer considering I don't have any charge and there's nothing...

Homework Statement a) A -10.1 nC point charge and a +18.9 nC point charge are 13.8 cm apart on the x-axis. What is the electric potential at the point on the x-axis where the electric field is zero? b) What is the magnitude of the electric field at the two points on the x-axis where the...

See this page: http://teacher.nsrl.rochester.edu/phy122/Lecture_Notes/Chapter25/Chapter25.html#Heading1" Why is there a negative sign in the formula for electrostatic potential V?

Homework Statement A thin rod extends along the z-axis from z=-d to z=d, carrying uniformly distributed charge along it's length with charge density lambda. Calculate the potential at P1 on the z-axis with coordinates (0,0,2d). Then find an equal potential at point P2 somewhere on the x-axis...

Opposite charges are built up between lightning clouds and the earth, which creates a potential, which causes lightening. Say you had a voltmeter that could handle infinite current and with leads hudnreds of meters long, and you stuck one lead onto a cloud which is about to create lightning...

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...

Electric potential at point x on the axis of a ring of charge density "eta" Homework Statement A circular disk of radius R and total charge Q has the charge distributed with surface charge density \eta = cr, where c is a constant. Find an expression for the electric potential at distance z on...

Homework Statement +1.0uC *-------3.0m---------*-----------3.0m---------* A B a) calculate the electric potential energy at A, 3.0m away from a point charge of +1.0uC. b) calculate the electric potential...

Homework Statement Three point charges, which initially are infinitely far apart, are placed at the corners of an equilateral triangle with sides "b". Two of the point charges are identical and have charge "q". If zero net work is required to place the three charges at the corners of the...