Electric fields Definition and 507 Threads

Homework Statement Two particles with positive charges q1 and q2 are separated by a distance s. Along the line connecting the two charges, at what distance from the charge q1 is the total electric field from the two charges zero. Homework Equations E= \frac{kq}{r^2} The Attempt at a...

Homework Statement At a particular moment, three small charged balls, one negative and two positive,are located as shown in Figure 13.46. Q1 = 1 nC, Q2 = 5 nC, and Q3 = -2 nC. Remember that you must first convert all quantities to S.I. units. 1 nC = 1 nanocoulomb = 1e-9 C. (a1)...

Homework Statement three point charges are placed at the following points on the x-axis +2 uC at x=0, -3uC at x=40 cm, -5 uC at x=120 cm. find the force (a) on the -3 uC charge, (b) on the -5 uC charge ans. (a) -0.55N ; (b) 0.15 N uC=nano coulomb Homework Equations Fm=qvB ...

Homework Statement An air-filled capacitor consists of a conducting sphere of radius a, surrounded by a concentric conducting spherical surface of radius b. A charge of 2Q is placed on the inner sphere and –Q on the outer surface. Calculate the electric field strengths E(r), (i) between the...

So if the electrocstatic force and electric field can be different directions which direction would a particle go? Would it depend on the field or the force, or something else like potential difference?

Can somone please explain why the following is not true: "Electric potential is zero whenever the electric field strength is zero" I know that the Field strength is the potential gradient, however why is the above true? Thanks in advance

A time-dependent magnetic field inside a superconducting solenoid is directed perpendicular to its circular section. This magnetic field is confined to a cylindrical volume of radius .05m such that the magnetic field, B = 0 for radial distances r > R. Find the rate of change of the magnetic...

Homework Statement A proton (m=1.67x10^-27) is suspended at rest in a uniform electric field E. Take into account gravity and determine E. Homework Equations FE=|q|E Fg=mg The Attempt at a Solution FG = mg FG = (1.67x10-27)(9.8) FG = 1.64 x 10-26 Since the force on the...

I'm being taught electromagnetism at university, but there's one definition that has been left slightly ambiguous for an electric field to be conservative I've been taught that 1) \nablaxE = 0 But I've also been taught that 2) \oint E.dl = 0 But I am not sure if 1) & 2) have to be true...

Multiple Point Charges Alright so the question is: A charge of 1.2x10^-3C is fixed at each corner of a rectangle that is 30cm wide and 40cm long. What is the magnitude and direction of the electric force on each charge? What is the electric field and the electric potential at the centre? I...

If anyone would like a go at this problem, they can just attach a paint file or something or send it to my e-mail: Heres the problem: 9. Three small, negatively charged spheres are located at the vertical of an equilateral triangle. If the magnitudes of the charges are equal, sketch the...

Homework Statement I have three questions concerning the electric field: 1- When calculating an electric flux for a spherical charge distribution my proffessor always writes "4 pi r2 E(r) = flux", where E(r) is the electric field. I don't understand this. I've tried to calculate the...

THe following is a homework assignment from AP Physics. Homework Statement Two large, flat parallel conducting plates are .10m apart. THe lower plate has a Voltage of 10v while the upper plate has a voltage of 20V. Point P is located .04m from the bottom plate. Find: a) THe magnitude of the...

What makes the electric field uniform? I learned it as a field that doesn't vary from place to place, but I'm trying to understand that better conceptually. For example, for problem #6 on the multiple choice http://www.enc.edu/~john.u.free/PY%20202%202006-7/Resources/Exam_1_05-06.htm...

Hi, I'd like to ask the good people of this forum for some help. Here's a problem I've been working on for a while, and I'm seriously at my wit's end. I guess there's something I'm missing here... Homework Statement Two insulating spheres have radii r1 and r2, masses m1 and m2, and...

Homework Statement So the question states: Four point charges, each of magnitude q, are located at the corners of a square with sides of length a. Two of the charges are +q and two are -q. The charges are arranged in one of the following two ways: (1) The charges alternate in sign...

A figure showing electric field lines has two charges, q and -q. There are 24 lines emanating from the +q charge. 15 of these lines terminate at -q. There are 24 lines terminating at the q- charge. What is the net flux through the surface surrounding the two charges?

"Three charges are placed at 100-m intervals along a horizontal line: a charge of –3.0 C on the left, 2.0 C in the middle, and 1.0 C on the right. What is the electric field E on the horizontal line halfway between the –3.0 C and 2.0 C charges?" When I do the calculation E = E1 - E2...

Homework Statement The potential difference between the accelerating plates of a TV set is about 20 kV. If the distance between the plates is 1.0 cm, find the magnitude of the uniform electric field in the region between the plates. Homework Equations V=ED so E=V/D where E is the...

Homework Statement Two concentric plastic spherical shells carry uniformly distributed charges, Q on the inner shell and -Q on the outer shell. Find the electric field (a)Inside the smaller shell, (b)between the shells, and (c) outside the larger shell Homework Equations integration(E *...

Two large flat metal sheets are a distance L apart. The separation L is small compared to the lateral dimensions of the sheets. Each sheet has a total surface area A, which includes both top and bottom surfaces of the sheet. The thickness of each sheet is very small compared to its lateral...

Homework Statement A thin circular sheet of glass of diameter 6 meters is rubbed with a cloth on one surface, and becomes charged uniformly. A chloride ion (a chlorine atom which has gained one extra electron) passes near the glass sheet. When the chloride ion is near the center of the sheet...

Homework Statement A rod of length 2L lies on the x axis, centered at the origen, and carries a line charge density given by t=T(x/L), where T is a constant. (a) Find an expression for the electric field strength at points on the x axis, for x>L (b) Show that for x>>L, your result has...

In a rectangular coordinate system, a positive point charge q = 9.00 nC is placed at the point x= 0.250 m, y = 0, and an identical point charge is placed at x= -0.250 m, y = 0. Find the x and y components and the magnitude and direction of the electric field at the following points. (a) Find...

Two 10cm-diameter charged disks face each other, 18 cm apart. Both disks are charged to - 30 nC. What is the electric field strength a point on the axis 5.0 cm from one disk between them? \eta/2\epsilon0 * [1-1/\sqrt{1+ R^2/z^2}] with \eta = -4.0 X 10^(-6) C/m^2 R=.05m z=.05cm for the left...

electron one is moving directly toward stationary electron two. the field at electron one due to electron one is proportional to 1/d^2. but the field at electron two due to electron one is less because electron ones field is compressed. it would seem from this that the forces on the 2...

I'm a little stuck on the theory behind this question: (in relation to a line of infinite charge: a wire) A hollow cylindrical metal tube with inner radius 2.5mm is now placed around the wire, to form a coaxil cable. What will be the charge per unit length on the inner surface of the tube...

I really just want to know if I'm doing this correctly, as I don't have access to the answer to check. Homework Statement A cylindrical shell of radius 7.00 cm and length 240 cm has its charge uniformly distributed on its curved surface. The magnitude of the electric field at a point 19.0 cm...

A long non-conducting cylinder has a charge density ρ = α*r, where α = 4.95 C/m4 and r is in meters. Concentric around it is a hollow metallic cylindrical shell. https://www.physicsforums.com/attachment.php?attachmentid=14741&d=1216404841 1. What is the electric field at 2 cm from the...

Homework Statement A point exists a distance D away from a rod of length L ( (point) |-----d-----| (ROD) ) So the point is in allignment with the rod, charged with a uniform charge density of -6.5uC/m Homework Equations E= Integral(k(dq/r^2) The Attempt at a Solution Im not...

Hi, I'm having a bit of trouble with the following problem. Any insight as to what I'm doing wrong? Homework Statement A solid metal sphere with radius 0.900 m carries a net charge of 0.130 nC. Find the magnitude of the electric field at at a point inside the sphere, 0.100 m below the...

[SOLVED] more electric fields Homework Statement four particles form a square of edge length a = 5.20 cm and have charges q1 = 10.8 nC, q2 = -8.87 nC, q3 = 11.6 nC, and q4 = -10.4 nC. What is the magnitude of the net electric field produced by the particles at the square's center? q1 is in...

I have a few questions about electric potential and electric fields. If two points have the same electric potential, is it true that no work is required to move a test charge from one point to the other? Does that mean that no force is required as well? Also, How much work is required to...

I just want to know if I'm even given enough information in this question to generate an answer. I don't need an actual answer. Thanks. "An electron is fired from a negative plate towards a hole in a positive plate. It then passes between two parallel plates that are 5 cm long and 3 cm...

Homework Statement A thick, spherical shell (inner radius a, outer radius b) is made of dielectric material with a 'frozen in' polarization \textbf{P} = \frac{k}{r} \textbf{\hat r} where k is a constant and r the distance from the centre. (There is no free charge). Find the electric field...

Homework Statement A metal ring 4.50 cm in diameter is placed between the north and south poles of large magnets with the plane of its area perpendicular to the magnetic field. These magnets produce an initial uniform field of 1.12 T between them but are gradually pulled apart, causing this...

[SOLVED] Capacitance and electric fields Homework Statement I want to find the capacitance of a parallel-plate capacitor consisting of two metal surfaces og area A held a distance d apart. First I find the electric field, which I know is \frac{\sigma }{{2\varepsilon }}. Then I use that the...

If an electric field wave oscillates north and south, and the wave is traveling straight up, then what direction does the magnetic field wave oscillate? east and west north and south up and down It does not oscillate; this situation is impossible. I know that magnetic...

Ok, this may borderline a homework problem, but I'm not quite grasping the concept of induced electric fields. So let's say that they exist a wire loop and solenoid. The switch in the circuit containing the solenoid is originally open and then closed. At this instant, we induce an emf in the...

Another question on electric fields. :( I have another problem I don't understand on electric fields. I thought I understood these after my last post, but I guess not. I'm guessing it has something to do with the signs of the forces, but I am not sure. Homework Statement Particles of charge...

What is the field near a square metal plate (with infinitesimal thickness) The answer is E = \sigma / \epsilon where \sigma = Charge per unit area \epsilon = relative permeabily Please help me to derive this result. using coulombs and then gauss' law

A small object carrying a charge of -5.50 nC is acted upon by a downward force of 24.0 nN when placed at a certain point in an electric field. What would be the magnitude and direction of the force acting on a proton placed at this same point in the electric field? Magnitude & Direction of the...

Homework Statement I need to solve the following wave equation: [\nabla^2 + \frac{\omega_a^2}{c^2}\epsilon]\mathbf{E_a} = -\frac{4\pi\omega_a^2}{c^2}\mathbf{P}^{(3)} Homework Equations \mathbf{P}^{(3)}=\chi^{(3)}:\mathbf{E_1E_1E_2^*} E_1 and E_2 are two electric fields with...

[SOLVED] Electric Fields- point charges Homework Statement Two point charges of charge 7.40 μC and -1.60 μC are placed along the x-axis at x = 0.000 m and x = 0.360 m respectively. Where must a third charge, q, be placed along the x-axis so that it does not experience any net force because...

Hello Sir , i am new to the site and so is not familar of that but i have question and i found u online so wish u to help me with that. Electric forces are used to accelerate small particles (like ink particles in a printers) but consider electrostatic action on macroscopic objects .Suppose...

Greetings everyone, I have a question about determining electric fields when given parallel planes of charge. In particular, I need some help getting the sign conventions straight in my head. I've attached 2 quick problems with solutions in a Word document so that perhaps you can help me to...

Homework Statement An electric dipole, consisting of charges of magnitude 2.60 nC separated by 7.20 µm, is in an electric field of strength 1400 N/C. (a) What is the magnitude of the electric dipole moment? (b) What is the difference in potential energy corresponding to dipole...

the electric field produced due to a time varying magnetic field is non-conservative in nature. does it follow gauss law?

Hi all, I am having a hard time understanding the following scenario (I'm quoting from page 305 of the "Electricity & Magnetism" textbook which you can access via Google Books): "Assume a simple model for an atom which consists of a point nucleus (+q) surrounded by a uniformly charged...

Homework Statement More of a general question: I have a situation where I have a conductor at eight volts and a conductor with zero volts. Just because there is an electric field, does that mean there is an electric current present in the system? And what is the direction? Homework...