Electric fields Definition and 507 Threads

Homework Statement An electron traveling horizontally east passes between two horizontal, oppositely charged plates and is deflected downward. Part A: Passing through the same space between the plates, in what direction (if any) a proton traveling horizontally east would be deflected? Part B...

My question is simple; yet, I can not find the answer. In the picture below, all variables are identical; the plate separations, surface area, etc. The only difference is the fact that example 1 has 2 different dielectrics. Better yet, it has a dielectric that doesn't extend the entire distance...

Homework Statement Three charges, Q1, Q2 and Q3 are located on a straight line. The charge Q3 is located 0.169 m to the right of Q2. The charges Q1 = 1.56 μC and Q2 = -3.03 μC are fixed at their positions, distance 0.268 m apart, and the charge Q3 = 3.18 μC could be moved along the line. For...

Good day everyone! n00bie here. I did do a search before I posted this... found a lot of info, most of which I couldn't apply to what I am doing (because I wouldn't know how). I have something that I am working on that creates an electric field to alter certain chemical compounds. The distance...

In electrostatics, ∇ × E = 0 so E that is a conservative field and there must be sources of E from which E flows. We know that this sources are the electrical charges given by Gauss' Law. But when B changes in time, ∇ × E = - ∂ B / ∂t. Now the Gauss' Law no longer applies and if there are not...

Let's say there's a question where there are two charges placed, and a point in between and above the line connecting the two charges forms a triangle like this: http://session.masteringphysics.com/problemAsset/1413940/2/p19.5.jpg What would one have to do in order to find the electric field...

Hi, Am I correct in thinking that for a positively charged spherical electrode, the charge is distributed radially from the entire surface of the sphere, and as such, the electric field is distributed in this way too? If an earthed electrode is then placed nearby, a high voltage would be...

Homework Statement "Show that the variation of the potential between the plates of a large parallel plate capacitor remains the same if the air between the plates is replaced by a conductive medium." Homework Equations E = σ/ϵ0 ; C = ϵ0A/d ' C = Q/V ; E = -dV/dx ; R = ρl/A The Attempt at a...

1. There are 2 negatively charged plates opposite each other. In between them, there is a vacuum tube (50 cm long), containing only 1 electron. Assume it is completely isolated. The charge value for the plates is equivalent to 10000 electrons. Initially the single electron is directly in the...

Discharging a capacitor through an inductor creates oscillations. This is about as much as I understand about it. I'm having a hard time explaining my question so I attached a pic. My questions: 1. In circuit A, are there oscillations in the inductor as the battery charges the first capacitor...

How would you generate extreme electric fields between two small surface area parallel plates.

Homework Statement a. Calculate the energy density of the electric field at a distance r from an electron (presumed to be a particle) at rest. b. Assume now that the electron is not a point but a sphere of radius R over whose surface the electron charge is uniformly distributed. Determine the...

I'm limiting my question to this field because it is the only one I know of with a certain degree of knowledge. I doubt they really exist because of the following reasoning: Coulombs law was stated because it makes mathematical sense (think of "force directly proportional to the charges and...

Hello PF, I am having a bit of difficulty understanding this question. Homework Statement "A thin wire with linear charge density λ is surrounded by a conducting cylindrical shell." (There is a hollow cylinder with a wire though it) "If the electric field must be zero inside a conductor, is...

Homework Statement A plastic rod of finite length carries an uniform linear charge Q = -5 μC along the x-axis with the left edge of the rod at the origin (0,0) and its right edge at (8,0) m. All distances are measured in meters. Determine the magnitude and direction of the net electric...

I know that a magnetic field will have an electric field bc there is charges, and they are moving. Thanks physicsforums!

Hello all. I am currently studying electromagnetism with Griffiths' books, and I have already donde electrostatic and magnetostatics. Now I am reviewing Ohm's law en emf concepts, but I have a doubt: In griffths book, when explaining ohm's law and emf, it seems to me that he assumes...

Why are magnetic fields and electric fields still considered different phenomena? Doesn't relativity and QFT explain that they are the same thing. A photon is a photon, isn't it? I mean, what is happening when two magnets repel? They exchange photons. What happens when two electrons repel? They...

Homework Statement Calculate the magnitude and direction of the electric field at point Z in Figure 13, due to the charged spheres at points X and Y. Homework Equations E = kq1/r^2 The Attempt at a Solution Determine each vector component: Ex = (9.0x10^9 Nm^2/C^2)(50.0 x...

Consider an equilateral triangle of side 15.6 cm. A charge of +2.0uc is placed at one vertex and charges of -4.0C uc each are placed at the other two, as shown in the diagram to the right. Determine the electric field at the centre of the triangle ANgle= 60 sides--> d1= d2=d3=0.156m...

Hi all, I am looking into induced electric fields by changing B fields inside layers of dielectric. For example, if a block of several layers of a dielectric material is placed inside a capacitor plate, the E fields inside each layer is shielded depending on the relative permitivitty...

Homework Statement 1. Use Gauss' Law to calculate the electric field at a radius of 5.0cm from the z-axis 2. Use Gauss' Law to calculate the electric field at a radius of 8.0cm from the z-axis 3. What is the surface charge density σmetal on the outer surface of the metal cylinder...

Homework Statement A uniform electric eld exists in a region between two oppositely charged parallel metal plates. An electron is released from rest at the surface of the negatively charged plate and strikes the surface of the positively charged plate, 2.00 cm away, in a time 1.8 * 10^{-8} s...

Electric fields vs magnetic fields? Ok, so in class last week, I had asked my professor about using the Lorentz Force Law to solve a particular problem. When he responded with "we only have a magnetic force from the current in the wire, so we don't have to worry about an electric field," that...

Homework Statement Consider a line of length L=0.950 m and uniform positive charge per unit length λ=2.9 μC. Point A is a distance x=0.23 m from the center of the line, while B is the same distance from the line but a distance y=0.28 m farther along the line; point C is a distance z=0.050 m...

My class hasn't delved into Gauss's Law much besides describing conductors at electrostatic equilibrium to have no net electric field or force within itself. For the picture, the question is: What are the magnitudes of the electric fields at: 1) r = a 2) r = 3/2 a 3) r = b...

I'm reading a book that deals with Gauss's law for electric fields in its differential form. I'm stuck now on a page that discusses taking deriviatives of the equation for a vector field: → A I'm familiar with the rules for deriviatives of products and quotients but unfortunately I cannot...

An Electric field has the following form in free space; E=Re{Eo exp[j(ωt-κy)\hat{i} I am confused as to why a unit i vector is in the expression for an electric field oscillating in the Y direction? and also what does the Re mean ? i was reading somewhere about it being to do with...

How do you determine the direction of fields at the location o the source. if given that the charge is negative, the electrostatic force is away from the source . Do you reason that since the test charge is positive and the charge is negative, it will go towards the center?

Homework Statement 5. An alpha particle ( 2 protons and 2 neutrons) is placed between two stationary, charged objects. It is 0.0030 m to the right of the object carrying a +1.0 X 10-12 C charge, and 0.0020 m to the left of the object carrying a -2.0 X 10-12 C charge. Draw a picture and...

Greetings PFers, Can someone help explain to me the difficulties of designing a device which utilizes static electric fields to map an objects’ internals and externals? My understanding is that as a electric field propagates through matter, it encounters absorption. I envision a device...

If there's a point charge Q at the center of a spherical surface(of radius a) made of conducting material that is connected to earth, why is the electric field past r>a zero ? Doesn't it imply that the spherical surface becomes charged with -Q ? And why is that? What would be the...

Just need someone to tell me if I'm doing this right. If I have accelerated a particle in which the mean free path is 50nm and I need the collision to be 5eV would this be correct in determining the required electric field strength? 5/.00000005 = 100MV/m

Homework Statement The electric field E1 is constant over the whole of one surface of parallelepiped and directed out of the surface. On the opposite surface is field E2 constant over the surface and is directed into the surface. the two surfaces forming an angle of 30 ° with the...

According to my textbook, the electrical field is defined as E = F/q where q --> 0, because we want the test charge to affect the other charges around it in the least possible way. It then goes on to say that qE = F is true for charges not strong enough to move the other charges. Why is that, if...

Problem #1 A slab of thickness 2a (extending infinitely in the y and z directions) with non-uniform charge density is parallel to the yz-plane. The charge density is given by ρ(x) = γx2, -a < x < a where γ is a constant. 0, a < |x|. (a) Use Gauss's law plus symmetry to find...

reading this page : http://hyperphysics.phy-astr.gsu.edu/hbase/electric/potsph.html it says "The electric field inside a conducting sphere is zero, so the potential remains constant at the value it reaches at the surface:" if the electric field inside the sphere is 0, then wouldn't that...

Homework Statement Consider two “circulating” electric field configurations. Expressed in polar coordinates (s,φ,z) they are: (these expressions are not dimensionally correct) 1. E = (0,s,0) 2. E = (0,1/s,0) a. Calculate ∇×E for both configurations. b. Note that ∫E⋅dl≠ 0 in either...

Homework Statement An infinitely long, uniformly charged straight line has linear charge density λ1 coul/m. A straight rod of length 'b' lies in the plane of the straight line and perpendicular to it, with its enared end at distance 'a' from the line. The charge density on the rod varies...

In the absence of external forces, the electric field inside a conductor is supposed to go to zero. This is because if any field were to exist, then the charges in the conductor would experience force and continue moving until they canceled the field. However, is it true that for any system a...

Homework Statement A,B,C,D are four 'thin',similar metallic parallel plates,equally separated by distance d,and connected to a cell of potential difference(V) as shown in the attachement. Write the potentials of A,B,C,D. If B and C be connected by a wire,then what will be the potentials...

Hi guys, brand-new simpleton here. Quick question: would it be possible to stop ice formation on a cold surface with an electromagnetic field? How strong should it be (if possible)? Thank you!

hello , could someone please remind me I have forgotten a few things. So the electric field is perpendicular to the conductor and the flow of charge. So if i have a pipe and in the pipe flows a conducting gas or a plasma , now around the pipe I have a simple copper wire wound in many many...

Hey. Let's say you have an infinitely wide and long disk with a thickness h. Inside the disk, there is a constant charge density ρ0. Why would the electric field lines be perpendicular to the disk? Can somebody explain how symmetry and such generally affect electric field distribution of a...

Homework Statement Two point charges are placed at the opposite corners of a rectangle as shown. What is the Electrical Field magnitude at each point due to the charges?Homework Equations Pythagorean theorem, E=kq/r^2The Attempt at a Solution r= square root of .8^2 +.4^2 =.89 E= 8.99x10^9 X...

Hey guys, just got a question at school and the last part makes no sense. I replicated it almost exactly, except for the diagram. Just imagine the dotted line is a solid line indicating the electric field lines. Ignore the 4 dots around X, it was just to keep the field lines in line.Question 4...

Homework Statement 1. If the electric field is zero at a point, the potential must also be zero at that point 2. If the electric potential is zero in some region of space, then the electric field must also be zero in that region. 3. If the electric field is zero in some region of...

Homework Statement Is it possible to create an electrostatic field E(x) (in 3 spatial dimensions x and E is a vector of course) such that i) E(x) = a × x (cross product) ii) E(x) = (a.x) b (dot product between a and x) where a,b and non-zero vectors that do not depend on time and the...

Homework Statement Heres the probelm: http://imgur.com/TbzJxVa Homework Equations e = kq/r^2 The Attempt at a Solution q-p Ex = (9*10^9)(4)/(0.80)^2 = 5.625*10^10 Q-p E1 = (9*10^9)(6)/(1)^2 = 5.4*10^10 Ex = E1sin45 = -3.82*10^10 Ey = E1cos45 = 3.82*10^10 P p =...

calculating electric fields due to continuous charge distributions? a question I came across doing some electric field questions, and the answer was really confusing. Homework Statement Charge is distributed along a linear semicircular rod with a linear charge density λ as in picture...