Electric field Definition and 1000 Threads

Homework Statement A dielectric sphere of radius R with uniform dielectric constant ε has an azimuthally symmetric density charge σ = σ0 cos θ placed on the surface. Outside the sphere is vacuum. (a) Obtain the electrostatic potential inside the sphere, φin. (b) Obtain the electrostatic...

Hi, just trying to better understand this concept of electromagnetic radiation. My understanding thus far is that it is a traveling disturbance in the electric field. This picture here seems to help me see what is happening...

The electric field in a 2.5mm×2.5mm square aluminum wire is 2.1×10−2 V/m . What is the current in the wire? The answer is I=4.65A. But my question is according to Gauss law, the electric field inside the conductor is zero. then how come this question says "The electric field in a 2.5mm×2.5mm...

Hi. Is the Maxwell equation $$\nabla\cdot\vec{E}=\frac{\rho}{\varepsilon_0}$$ even true in the stronger form $$\frac{\partial E_i}{\partial x_i}=\frac{\rho}{3\cdot\varepsilon_0}\enspace ?$$ I guess not, since I haven't found a source suggesting this. But shouldn't the isotropic electric field...

Homework Statement Find the expression for the electric field at point M(a,a,0) if the linear charge density is known ( ##Q'## ) Homework Equations 3. The Attempt at a Solution [/B] I tried something like this and would like your feedback on it. I separated the triangle into three parts...

Homework Statement In the picture below it is asked that i calculate the resultant electric field if the linear charge density is known. Calculate the resultant electric field of a charged semicircle wire (positioned as in the picture) at some point M on the Z axis if the linear charge density...

Imagine you have two identical metal balls, each carrying the same amount of charge, but with one ball being positive and the other negative. When you bring them close together, there will be polarization, so you can no longer treat the balls as point charges. How does one find the charge...

Homework Statement A metal sphere with a diameter of 10 cm has a charge distribution of 1.09085 x 1018 electrons/cm2 on its surface. What is the electric field strength at a distance of 25 cm from the surface of the sphere? (Answer: 5.5 x 1012 N/C) Homework Equations I wasn't given any...

I know there is a lot of answers out there, but so far none really answered my question. Say I have this radioactive conductor sphere that has a negative charge. Of course, all the negative charges will be spread evenly on the surface and there SHOULD be 0 electric field inside the conductor...

1. Homework Statement Calculate the resultant electric field acting on some point ##x##. The electric field is generated by a long thin rod and the line charge density is given. ##p_l=\frac{dQ}{dL}## Homework Equations 3. The Attempt at a Solution [/B] I have uploaded two images, one of the...

Homework Statement Dr. X has an infinitely long superconducting solenoid with n turns per unit length and a power supply to drive arbitrary current wave forms through the solenoid's winding. The power supply can drive DC currents, temporarily ramped currents, sine wave currents, etc...

Homework Statement A line of charge of uniform density ρl occupies a semicircle of radius b as shown in Fig. P4.10. Use the material presented in Example 4-4 to determine the electric field at the origin. Homework Equations dE = kdQ/r^2 The Attempt at a Solution I'm trying to understand the...

Homework Statement I just wanted to make sure I understood the difference between the two. Coulombs law is the force between two charges. Two charges that are physical(maybe not the right word) located on some axes. We can use the equation F=k(q1 * q2 * r(hat))/r^2 r^2=|r| = |x-x'| where r hat...

Does electric current also produces electric field (in addition to magnetic field) at a typical stationary point? In other words, electric current includes the moving charges. Do these charges produce electric field at a stationary point? Or, does the electric field of these charges come into...

Homework Statement Imagine a particle with charge +Q moving with constant horizontal velocity passing perpendicular to electric field between two parallel plates. The length of the plates is L. Therefore, is the time spent in the field (well, between the plates), simply the length/horizontal...

Homework Statement The Spherical region a<r<b carries a charge per unit volume of $$\frac{A}{r}$$, where A is constant. At the center there is a point charge q. Find A such that the Electric field in a<r<b is constant. Homework Equations Law of superposition and $$E=\frac{kq}{r^2}$$ The...

When solving the differential equations for an electromagnetic wave you get out that the electric and magnetic field oscillate in phase. But when considering a oscillating dipole, the electric and magnetic field at a point close to the dipole are a quater period out of phase. Can someone please...

Hi. I learned that in an ideal conductor in a circuit, the voltage drop is zero. But how does this agree with the basic definition of voltage $$U_{AB}=\int_A^B \vec{E}\cdot d\vec{s}\enspace ?$$ The electric field inside a conductor only vanishes in static conditions, but in an electric circuit...

Homework Statement What is the magnitude E of the electric field at point P? Throughout this part, express your answers in terms of the constant k, defined by k = 1/(4πE0) To solve this question, I am trying to walk through the hint process. Question 1: Find the magnitude dE of the electric...

1. Passage of current via coil creates magnetic field (fig a), similarly external magnetic field linked to coil when changed created electric current in the circuit connected ( Faraday's em induction fig b). 2. Charging of capacitor using voltage source creates electric field in the capacitor...

While I was studying with electric field about cylinder, I learned that for a very long cylinder, the electric field in the hollow of cylinder will be zero. http://physics.stackexchange.com/questions/156789/electric-field-of-hollow-cylinder However, I couldn't accept this intuitively, and...

Hi. I understand a lightning rod reroutes the current of a lightning around an object, e.g. building. The lightning will preferably strike the rod because the electric field is strong at sharp points and the air is more likely to be ionized there. But does it also avoid lightning by giving off...

Homework Statement I'm trying to find the electric field at the origin <0, 0, 0> due to a quarter of a ring with +Q charges on it. The quarter of the ring lies on the +y-axis. Due to symmetry, the x-components of the electric field will cancel out, leaving only the y-component of the electric...

Find E(r) inside and outside a uniformly charged spherical volume by superposing the electric fields produced by a collection of uniformly charged disks. a+b) Given equations, sketch of problem This is the equation in the handbook for a disk (but in the exercises the z becomes x, without loss of...

Consider Gauss's law in ##1## space and ##1## time dimension. In this case, ##\int\ \vec{E}\cdot{d\vec{A}}=\displaystyle{\frac{Q}{\epsilon_{0}}} \implies 2 E =\displaystyle{\frac{Q}{\epsilon_{0}}} \implies E =\displaystyle{\frac{Q}{2\epsilon_{0}}}##, where the factor of ##2## comes from the...

Homework Statement https://gyazo.com/d502fb408d6224ffa70700cf047bad20 (link to problem: #4). [moderator edit: Image inserted for clarity] A total charge Q is distributed uniformly over rod length L. The rod is aligned on the x-axis, with one end at the origin and the other at point x=L. a)...

Can anyone explain in simple terms what the term screening means? My intuition is that a metal is a good screener because in the presence of an external electric field its free electrons will rearrange themselves such that the electric field is zero inside the metal. But I am having a hard time...

Homework Statement A long metal pipe of square cross-section is grounded on three sides, while the fourth (which is insulated from the rest) is maintained at constant potential ##V_0##. What is the electric field just outside the section opposite to ##V_0##? Homework EquationsThe Attempt at a...

Let's say you have two particles that are the same in magnitude but have opposite charges like the equation down below: E1 = -q*k/r^2 E2 = q*k/r^2 ETotal = q*k/r^2 + -q*k/r^2 = 0 Does this mean that the electric field of both these charges cancel out each other? Then what is the electric...

Hi, I found this on http://farside.ph.utexas.edu/teaching/302l/lectures/node32.html "Consider a charge placed in a uniform electric field (e.g., the field between two oppositely charged, parallel conducting plates). Suppose that we very slowly displace the charge by a vector displacement in...

Homework Statement WITHOUT using Gauss's law calculate the electric field at all points outside and inside an infinite cylinder with circular cross section of radius b and charge density ρ Hint: Use cylindrical coordinates and place the target charge on the x axis..Homework Equations E =...

I am looking to use Gauss's law to find the electric field in ##1+1## dimensional spacetime: ##\int \vec{E}\cdot d\vec{A}=\frac{Q}{\epsilon_{0}}## Now, for a point charge in ##1+1## dimensional spacetime, the Gaussian surface is the two endpoints (a distance ##r## away from the point charge)...

Hi, A time-varying (sinusoidal) voltage source is applied to a parallel plate capacitor of length d. Then the E field will vary according to E(t) = V(t)/d. However, this suggests that, for any given time, the E field is constant with respect to spatial coordinates. Therefore, the curl of E is...

Homework Statement Particle 1 of charge +4.0 μC and particle 2 of charge +1.0 μC are held at separation L=10.0 cm on an x axis. Particle 3 of unknown charge q3 is to be located such that the net electrostatic force on it from particles 1 and 2 is zero. In the included figure, particle 1 is...

Homework Statement I'm looking at an electric field plot around four (4) + and - point charges in free space. There are several points where the electric fields come together and make right-angled turns (in the limit). Is there a name for these points? Especially is there a traditional name for...

Hi. Different interpretations of QM have different opinions about the ontology of the wavefunction, i.e. if it really, physically exists or if it is "just" a mathematical tool needed to calculate the outcome of measurements. The QM interpretations comparison table on Wikipedia summarises the...

Homework Statement [/B] A thin, horizontal, 11-cm-diameter copper plate is charged to 4.3 nC . Assume that the electrons are uniformly distributed on the surface. What is the strength of the electric field 0.1 mm above the center of the top surface of the plate?Homework Equations [/B] E=...

Is this the correct equation to find the electric field at point p from a dipole?

Hello. I'm now taking accelerator physics class and the lectures said in the thermionic electron gun, anode metal mesh should be grounded in order to prevent electrons which traveled beyond the mesh from coming back due to the electric field lines. Without grounding of the anode, I believe...

Homework Statement An electron is released from rest in a weak electric field given by = -2.70 10-10 N/C [PLAIN]http://www.webassign.net/images/lowercase/jhatbold.svg. After the electron has traveled a vertical distance of 1.4µm, what is its speed? (Do not neglect the gravitational force on...

Homework Statement In a cubical volume, 1.05 m on a side, the electric field is given by the formula below, where E0 = 1.25 N/C and a = 1.05 m. = E0(1 + z/a) i + E0(z/a) j The cube has its sides parallel to the coordinate axes, see the figure. Determine the net charge within the cube...

Homework Statement Suppose the nonconducting sphere of Example 22-4 has a spherical cavity of radius r1 centered at the sphere's center (see the figure). Assuming the charge Q is distributed uniformly in the "shell" (between r = r1 and r = r0), determine the electric field as a function of r...

Homework Statement Suppose electrons enter the electric field midway between two plates at an angle θ0 to the horizontal, as shown in the figure, where L = 5.1 cm and H = 1.1 cm. The path is symmetrical, so they leave at the same angle θ0 and just barely miss the top plate. What is θ0? Ignore...

I'm studying for my physics exam and there is a figure on the book physics for scientists and engineers 4th edition by giancoli that i just don't understand. I know that the electric field of a negative charge points toward it and the electric field of a positive charge points away from it Also...

Homework Statement Lets say, there is a non-uniform charge distribution, given as in a spherical shell that has a cavity with radius a and the radius b to the outer surface. I am wondering if the field is discontinuous just on the surface of this sphere. Homework Equations...

Homework Statement A semi-circle of radius R has a charge Q uniformly distributed over its length, which provides a line charge density λ. Determine E at the origin. Homework EquationsThe Attempt at a Solution https://www.physicsforums.com/attachments/105239 I can tell by argument of...

NOTE: Other threads suggest solving it with Gauss' Law. I'd like to see an approach through direct integration, no full followthrough necessary.. 1. Homework Statement Consider a sphere with a uniform distribution of charge ρ (ro). Inside the sphere is a cavity (spherical). Calculate the...

Homework Statement [/B] A square plate of side-length L, charged with uniform surface charge density η. It is centred at x = y = z = 0 and orientated in the z = 0 plane. The task is to determine the z-component of the electric field at the point r(x, y, z) = r(x, 0, d), offset along the...

Homework Statement There's a uniform infinite line charge with the charge density λ. A point particle with charge q moves with a velocity v parellel to infinite line. What is force exerted on point particle? What is magnetic field seen in ths moving frame(particle frame)? Homework Equations...

Homework Statement In the figure a nonconducting spherical shell of inner radius a = 2.07 cm and outer radius b = 2.51 cm has (within its thickness) a positive volume charge density ρ = A/r, where A is a constant and r is the distance from the center of the shell. In addition, a small ball of...