Electric field Definition and 1000 Threads

Homework Statement There's a charged semicircle, the ends of which are on the x-axis and it extends into the positive y-axis. It has uniform line charge density. I need to find the electric field at an arbitrary point on the x-axis that's not the origin. Homework Equations I don't know. The...

Homework Statement What is the electric field at the center of a hemisphere bounded by r=a, 0<θ<pi/2 / and 0<∅< 2pi with a uniform surface charge density? Homework Equations (1/4piε0) ∫ p(r') ((r-r')/[r-r']^3) dr' The Attempt at a Solution Forgive my formatting ds= (r^2)sinθdθd∅ (In direction...

Homework Statement Homework Equations ' The Attempt at a Solution Please excuse the poor writing. I believe it should be legible enough, but if you have any questions, i'll clarify or rewrite it. Please excuse the poor writing. I believe it should be legible enough, but if you have any...

Homework Statement Two parallel plates 1.40 cm apart are equally and oppositely charged. An electron is released from rest at the surface of the negative plate and simultaneously a proton is released from rest at the surface of the positive plate. How far from the negative plate is the point at...

Field at End of Line of Charge 2 A charged rod of length L=7.10 m lies centered on the x axis as shown. The rod has a charge density which varies according to λ=ax^2 where a=−20.2 μC/m^3 . What is the x component of the electric field at a point on the x-axis a distance of D=3.70 m from the...

1. Homework Statement Hi everyone, I am having trouble solving this question. I know that the right answer is d. Homework Equations No equations here, only conceptual stuff. The Attempt at a Solution Say I have the following points: A and B A...

Homework Statement A thin semicircular rod is broken into two halves. The top half has a total charge +Q uniformly distributed along it, and the bottom half has a total charge -Q uniformly distributed along it. A negative test charge is placed at points A, B, and C. *Image attached* Consider...

Homework Statement A thin semicircular rod has a total charge +Q uniformly distributed along it. A negative point charge -Q is placed as shown. (Point C is equidistant from -Q and from all points on the rod.) *Image Attached* Let Ep and Er represent the electric fields at point C due to the...

Hi everyone, I am having problems figuring out how to solve a particular problem. Because I was not able to access PhysicsForums recently, I typed everything about my issues into a pdf file that I have attached below. I am grateful for your help in advance, and make it a great day...

Hello A friend of mine asked me if he could improve the (amateur) characterization of minerals by studying the absorption spectra during the application of a magnetic field. I thought that maybe the electron cyclotron resonance could work, but then I noticed that very low temperatures are...

Is the direction of electric field save as the direction of (conventional) current?

1. Homework Statement i was solving the 2008 semi final us physics olympiad paper when i got stuck on question B2 in part 2 http://www.aapt.org/Programs/contests/upload/olympiad_2008_semi-final_soln.pdf the link takes you a pdf with questions and solution however i don't understand the soution...

When a charge placed at anywhere,then it produces a powerful field around itself,is called electric field. It is exist whenever charge exist.And charge takes very very small time in propagate electric field.

It is a simple arrangement. Imagine that we have an empty cubic box. Outside the box the electric potential is infinite. Imagine that you put an electric charge at the geomectric center of the box. What is the field around this charge? In other words, the tool I have to calculate the field...

Homework Statement https://imgur.com/zEoCpc0 I am trying to figure put the angle and my attempt is tanx=sy/sx (I have calculated a value for the distances) But my book is saying: tanx =vy/vx I don't understand why my way of solving it is wrong... I don't get the same answer for x :/

Homework Statement a) Find the net force on charge 1. b) What is the net electric field acting on charge 1? Please see the attached files to view the image that goes with the questions above. Homework Equations I'm having trouble with this unit in general and I'm not to confident in these...

I understand that as a solid melts, it increases can increase in polarizability of the medium, and increase the Dielectric constant (K). -ex. like dissolving NaCl and having ions in solution. Why does Thermal motion reduce the polarizability of the medium, thus decreasing the dielectric...

Homework Statement What is the Net force (include direction) acting on charge Q2 due to Q1 and q? (ans: Fnet = 174N right) Homework Equations F=kQ1Q2/r2 E=F/QThe Attempt at a Solution I've figured out a) and b). It's just c) that's giving me trouble. I tried using the first equation - (9.0 x...

Homework Statement What is the electric potential at P due to charges Q1 and Q2...

Hi, If I had a charged parallel plate capacitor which was not connected to a circuit (so the charges stay on the plates) creating an electric field strong enough to cause ionization, and I then fired a neutral atom between the charged plates (the charge starts outside of the electric field)...

Sorry i have one question to ask how to integrate the electric field of the square sheet( see the pink circle below) it looks hard for me thank you very much

I'm confused with the electric field inside a sphere. The book said that E=keQr/a^3 While one of the properities of electrostatic equilibrium mentioned that the E-field is zero everywhere inside the conductor. Are there any exceptional cases? Thanks in advance.

Electric Field Strength is defined in many books as F/Q, where F is force and Q is the test charge. but why is that? why not F/(2Q)? or F/Q^2?, is this word "strength" related to stress-strength as in mechanics?

Problem we are looking at :A laser beam has diameter 1.30 mm . The beam exerts a force of 3.7×10−9 N on a totally reflecting surface. What is the amplitude of the electric field of the electromagnetic radiation in this beam? (Emax) Relevant Formulas...etc.: I have the formula...

Homework Statement [/B]Homework Equations V= kq/r.[/B]The Attempt at a Solution For 8-8, I do not really know how to approach it. For 8-14 , I think that q2=-q1 and q3=q1+q2. I can now use V=kq/r and then find the equations for r>R3 , r=R3 , R2<r<R3 , r=R2 and R1<r<R2 and then graph...

The general formula to calculate maximim electric, Emax in concetric cylinder is Emax= V/a ln (b/a). But how does the formula differentiate if there are 3 inner cylindrical electrode?

Homework Statement In which direction would the electric field in the wire point if the wire were pulled to the right? Homework Equations Right hand rule F=qvXB The Attempt at a Solution My answer is downward. I am confused whether I should take the moving charges as positive or negative...

Homework Statement A non-conducting sphere of radius a carries a non-uniform charge density. The electrostatic field inside the sphere is a distance b from is center and is given by E = (b/a)4E0 (E0 being the maximum magnitude of the field.) a. Find an expression for E0 in terms of the...

Homework Statement Estimate the rms electric field in the sunlight that hits Uranus, knowing that the Earth receives about 1350 W/m2 and that Uranus is 19.2 times farther away from the Sun (on average) than is the Earth. Homework Equations I=cεoErms2 E=V/d The Attempt at a Solution Eearth=V/d...

Homework Statement Let me just put this here: http://i.imgur.com/dgcWAC3.png . Homework Equations E_flux=EA=(q_encl)/(permittivity) Area=4pir^2 The Attempt at a Solution Whenever I manipulate the above equations, I get a term of the form R/r, which implies, R being 5 cm, and r being the...

Take the case where the electron-beam is oscillating between two parallel metal plates, there will be alternating potential developed between the plates as metal tries to negate all external electric fields. My query is, (1) How to calculate the potential developed and possible way to simulate...

Homework Statement An infinitely long, hollow, conducting cylinder has a inner radius a and outer radius b and carries a linear charge density λ along its length. What is the electric field everywhere? Homework Equations ∫E⋅dA = Qenc/∈ Variables ∈ = permittivity constant a = inner radius b =...

Homework Statement For a given system, a conducting cylinder with radius ##r=a## with a linear charge density ##Q'## and a conducting surface at a distance ##z=h## from the cylinder, calculate the linear capacitance of the cylinder.Take that ##h>>a## ##C'=\frac{Q'}{U}## Homework Equations 3...

Hi there, in electrospinning, a positive charge of around 10.000Volt is applied to a needle, where a viscous polymer is extruded. There is a grounded collector in a distance of 15mm and the established electrical field generates electrostatic forces and draws a thin polymer jet to the...

Homework Statement [/B] Volume charge density in some space is given by a function ##ρ_v(x)=-ρ_0\frac{x}{a}e^{\frac{-x^2}{a^2}}## where ##ρ_0, a## are positive constants. Determine the electric field vector in arbitrarily chosen point in space. Homework Equations 3. The Attempt at a Solution...

1. Homework Statement A flat ring, with radii ##b>a## like on the picture is charged with a surface charge density ##ρ_s=ρ_0\frac{b}{r}## where ##ρ_0=const.## Calculate the potential of the ring on the ##z-axis## by taking the reference point to be in the infinity. Picture below. 2. Homework...

Homework Statement Calculate the electric energy density at the surface of a 3.4 mm diameter copper wire carrying a 28 A current. Homework Equations u = (1/2) ε0 E2 The Attempt at a Solution With the electric energy density equation, I substituted in the equation for the electric field for an...

Hi. I'm a bit puzzled that the classical formula for the intensity of a monochromatic, linear EM wave $$I=\frac{1}{2}\cdot c\cdot \varepsilon_0\cdot E_0 ^2$$ seems to be independent of frequency whereas I find for the energy of a mechanical wave (e.g. on a string with total mass ##M##)...

Homework Statement See picture above Homework Equations Int (E dot dl) = Int (B dot dA) The Attempt at a Solution Where did I go wrong? Is there a sign error possibly or am I off conceptually? [/B]

Homework Statement We are given a disk with negligible thickness, a radius of 1m, and a surface charge density of σ(x,y) = 1 + cos(π√x2+y2). The disk is centered at the origin of the xy plane. We are also given the location of a point charge in Cartesian coordinates, for example [0.5,0.5,2]. We...

I came across these videos that show how electric field looks around the dipole antenna at three different distances Far field Near field Something between far and near field That got me thinking - there is a point when the field is reversing and the electric field closes into a loop and...

Homework Statement Around a point charge there are three points: A, B and C. Determine the electric field vector for those points. Also, determine the force vector for q0 if it was in point B. Q = 10 µC, a = 1 m, b = sqrt(3) m, q0 = 10 pC 2. The attempt at a solution Here is the attempt at a...

Does a positive test charge follows along the path of electric field lines if it is free to do so? I mean the trajectory of the charge is along the electric field lines and the field lines are not necessarily straight.

Homework Statement A metal sphere of radius ##a=1cm## is charged with ##Q_a=1nC##. Around a sphere is placed a spherical shell of inner radius ##b=2cm## and outer radius ##c=3cm##. The electrical potential of the shell in refenrence to a point in the infinity is ##V=150V##. The spheres are in...

According to Faraday's Law, Time-Changing magnetic field creates an induced current in a closed conducting loop. This is the equation: ##\nabla \times \mathbf{E} = -\frac{\partial \mathbf{B}} {\partial t}## 1-) Does this current (##\nabla \times \mathbf{E} ##) have to be an alternate...

hi, i want to ask explanation that if in front of electric fields lines comes a metal plate, than as far i know electric field does not pass through it, but how would i expalin as electric field can exert force on free electrons.

I am trying to learn how parity and time reversal transform the electric field, ##A_\mu## and ##\partial_\mu##. In other words what: what are ##P \partial_\mu P##, ##T \partial_\mu T##, ##T A_\mu T## and ##P A_\mu P##? My first guess was that ##P A_\mu(t,\vec{x}) P = A_\mu(t,-\vec{x})##, ##T...

Homework Statement For what electric field strength would the current in a 2.0-mm-diameter nichrome wire be the same as the current in a 1.0-mm-diameter gold wire in which the electric field strength is 0.0095 N/C? dn = .002m dg = .001m Eg = .0095 N/C ρn = 100 * 10-8 Ωm ρg = 2.44 * 10-8 Ωm...

The common presentation for free field quantization proceeds with the Lorentz and Coulomb (##\phi = 0, \,\nabla \cdot \mathbf{A} = 0 ##) constraints. Then ##A## can be defined $$\mathbf{A} \propto \iint \frac{d^3 p}{\sqrt{2\omega_p}}\sum_{\lambda} \Big(e^{i\mathbf{p}\cdot...

We have this situation an electron comes flying in electric field between two capacitor plates. Let's say that voltage is 12V and distance between plates is 1m. Electric field E=U/d=12V/m. Plates are connected to the battery just initially. The battery is later disconnected. If electron comes...