Electric fields Definition and 483 Threads

Homework Statement Two charges each +4 microcoloumbs ar eon the x axis, one at the origin and one at x=8m. Find the electic field at the x-axis at x=10m and x=2m. Homework Equations E=kq/r The Attempt at a Solution I tried the x=10m first. What I did was take E1=kq/r^2, or...

Why black holes can have static electric fields? The gravitation of black hole is so strong that nothing can escape from it ! Why black holes can have static electric fields around with it? Thank you in advance！

1. The magnitude of the electric field between two plates of a parallel plate capicitor is 4.7 x 10^4 N/C, if the charge on each plate increases by a a factor of 3, what happens to the electric field? increase by a factor of 3 or 9? decrease by a factor of 3 or 9? not effected? 2...

If a problem asks you to find the electric field at a certain point, do you add up the field vectors as if they were forces on a positive test charge? For example:

I am having trouble figuring how the info given relates to electric and magnetic fields. Homework Statement A laser emits 1.38x10^18 photons per second in a beam of light that has a diameter of 1.96 mm and a wavelength of 518.0 nm. Determine each of the following for the electromagnetic wave...

Homework Statement 3. Two electrons are fired at 3.5 x 10^6 m/s directly at each other. a)Calculate the smallest possible between the two electrons. Homework Equations Ek= 1/2mv^2 Ee= kq1q2/r The Attempt at a Solution I made the Ek and the Ee equal, but i keep on getting the...

Homework Statement A negative charge of 2.4 X 10^-6 C experiences an electric force of magnitude 3.2 N, acting to the left. a. Calculate the magnitude and direction of the electric field at that point. b. Calculate the value of the field at that point if a charge of 4.8 X 10^-6 C replaces...

Can any 1 please help me out with this...i'm not able to understand the term polarization when associated with electric fields??

it is known that in metals the electric field is zero because there are free charges inside that rearranges in such a way that it cancels the external electric field. If the external electric field is large enough, so large that all the free charge inside cannot rearrange itself to cancel the...

I am having some problem with the formulas for calculating the electric fields of an infinite line of charge and an electric dipole. I don't understand conceptually why they are the way they are. Can someone explain? Any help is appreciated! [Note: K=1/(4*pi*epsilon_o), lambda=linear...

Homework Statement A point charge q = +2.6 µC is placed at each corner of an equilateral triangle with sides 0.13 m in length. What is the magnitude of the electric field at the midpoint of any of the three sides of the triangle? Homework Equations E=(kq)/r^2 Fx=(F1+F2)cos...

Homework Statement A very long, straight wire has charge per unit length 1.47×10^10 At what distance from the wire is the electric field magnitude equal to 2.57 N/C Homework Equations E = lambda / (2*pi*E_o*r) E_o = 8.85*10^-9 The Attempt at a Solution 2*pi*E_o*E / lambda...

Hi, Homework Statement You've hung two very large sheets of plastic facing each other with distance d between them, as shown in Figure P26.50 ( http://i137.photobucket.com/albums/q208/infinitbelt/p26-50-1.gif ... ). By rubbing them with wool and silk, you've managed to give one sheet a...

Trying to work this one out. If you have two charges Q1 and Q2 separated by a distance of x then how do you show what distance from the charge Q1 is the total electric from the two charges zero. I know that Enet =E1 +E2 and if i use coulombs law i get: KQ1/x^2 +KQ2/x^2 the K cancles...

I haven't taken any course in quantum field theory or read any advanced books about it, but I would like to make what I think is a deduction. An electric field can be explained by changing magnetic field. Provided that some property of this changing magnetic field was met, the electric field...

In Millikan's experiment, an oil drop of radius 0.9493 µm and density 0.876 g/cm3 is suspended in chamber C (Figure 22-14) when a downward-pointing electric field of 1.92 105 N/C is applied. Find the charge on the drop, in terms of e. (Include the sign.) So, to do this problem, i know that...

magnetism and electric fields Hello all. I'm new to this, but I would really appreciate any help, I'm absolutely terrible at physics... 1) In a trial of Millikan's oil drop experiment, we find that the electric field required to suspend a tiny oil particle with mass 1.46x10^-14 kg is...

Purcell said "One must be alert for every opportunity to bring the students into the world where an electric field is not a symbol merely, but something that crackles." Why does an electric field crackle? Is it because electric fields are lines which connect charges, enabling them to exert...

Not sure how to go about proving that if E and B are perpendicular in one Lorentz frame they are perpendicular in all Lorentz frames.

Here's the question: A square plate of copper with 50.6 cm sides has no net charge and is placed in a region of uniform electric field of 80.9 kN/C directed perpendicularly to the plate. a. Calculate the charge density of each face of the plate. b. Calculate the total charge on each...

Here is the question: Three identical small Styrofoam balls (m = 1.93 g) are suspended from a fixed point by three nonconducting threads, each with a length of 49.0 cm and with negligible mass. At equilibrium the three balls form an equilateral triangle with sides of 29.2 cm. What is the common...

I have a question about electric fields: Here is the question: Three identical small Styrofoam balls (m = 1.93 g) are suspended from a fixed point by three nonconducting threads, each with a length of 49.0 cm and with negligible mass. At equilibrium the three balls form an equilateral...

Consider a long horizontal conducting wire with charge density = 5.70*10^-12 C/m. A proton (mass = 1.67*10^-27 kg) is placed and released 0.820 m above the wire. What is the magnitude of initial acceleration of the proton? My thought is: a=q*E/m and E is: 2*k*charge density/distance...

An iodine (-1) and a chloride ion (-1) interact in a vaccum. a. What is the force which each exerts on the other from a distance of 2.0 x 10^-9 m? b. What is the eletric field that the iodine ion experiences from the chloride ion? toward which ion does the electrical field vector point...

Hi, I am currently stuck on the following questions. Any help is greatly appreciated. thank you *all question are algebra based 1) A point charge of -0.90 microC is fixed to one corner of a square. An identical charge is fixed to the diagonally opposite corner. A point charge q is fixed to...

Hi, sorry if this is a frequently asked question. I was reading up on black holes with electric charge and I was wondering how the electric field is able to propogate out of the singularity and the event horizon, if anything moving at the speed of light cannot escape. The only explanation...

Hello, everyone. I have a problem that I solved using Gauss's Law. However, I am unconfident in my answers, as I have very little experience with Gauss's Law. The surfaces of two large (i.e. infinite) parallel conducting plates have charge densities as follows: \sigma_1 on the top of the top...

this isn't a quack question (is my monitor giving me cancer...etc) but are there any studies involving effects on humans of considerable static electric fields? say low thousands of Vm-1? what could be possible long/short term effects?

Each quare centimeter of the surface of an infinite p;ane sheet of paper has 2.5 X 10^6 excess electrons. Find the magnitude and direction of the electric field at a point 5 cm from the surface of the sheet, if the sheet is large enough to be treated as an infinite plane. This is an odd...

Lets say, hypothetically of course, that i know somebody that had something that, with that something being charged, was generating a strong electric field(or maybe electromagnetic waves?) that was emitted in all directions for infinity, if this hypothetical friend were to put a faraday cage...

"Electric fields are not always superposable" In my Physics textbook by Resnick, Halliday and Krane (Wiley publications), it is mentioned that (pg. 575), " the principle of superposition of electric fields is not at all obvious and may fail in the case of very strong electric forces." Can...

I'm completely stumped on three questions, please help... 1. Particle 1 of charge +1x10^-6C and particle 2 of charge -3.0x10^-6C are held at separation L=10.0cm on an x axis. If particle 3 of unknown charge q3 is to be located such that the net electrostatic force on it from particles 1 and 2...

I've been doing some questions and I'm completely stuck on three of them. I tried thinking of how to tackle them but I'm coming up blank. 1. A charge of q is distributed uniformly throughout a spherical volume of radius R. Setting V = 0 at infinity, show the potential at a distance r from the...

emf, current, electric fields...what direction is everything moving? This is a very simple question but I can't seem to figure out the actual direction that things are moving in a simple circuit. Suppose you have a simple circuit consisting of a battery and a resistor: The electrons inside the...

Consider a uniformly moving charged particle (moving along the x-axis say). Consider an observer a light minute away from the origin, on the y-axis. Now, when the particle crosses the origin, the observer measures that the electric field points towards the origin. Why is this? This seems...

Electric field lines always point toward: (_) positive charge (_) a region of higher potential (_) ground (_) a region of lower potential (X) none of these Now, i thought that electric fields point towards the negative charge. I submitted my homework, and i missed it. I...

We usually go over stuff after getting the assignments, so I have no clue how to start this question. Figure 23N-14 shows the deflection-plate system of a conventional TV tube. The length of the plates is 3.2 cm and the electric field between the two plates is 10^6 N/C (vertically up). If the...

Determine the acceleration of a proton (q = +e, m = 1.67 E -27) in an electric field of intensity 500 N/C. How many times is this acceleration greater then that due of gravity I'm not so understanding on todays lessons teh 2 formulas I can recall are f = q*e and e = f/q but i don't see...

I need help on a few questions. 1.An alpha particle has a positive charge of 2e and a mass of 6.6 x 10^-27 kg. With what velocity would the particle reach the negative plate of a parallel plate apparatus with a potential difference of 2.0 x 10^3 V. a)if it started from rest at the positive...

Hi, I am confused about the electric field within a conductor. My textbook states that it is zero when charges at rest. Does this mean, the there is no electric field within the metal part of the conductor (let's assume this conductor is a hollow sphere), or the actual "empty" inside core of...

A positive point charge q is placed at x=a and a negative point charge -q is placed at x=-a. a: find the magnitude of the electric field and the direction at x= 0. b: derive an expression for the electric field at points on the x-axis. use results to graph the x-component of the electric field...

The period T of an Earth satellite is related to the radius R of its orbit by the equation T^2 = A R^3 where A is a constant. The moon may be assumed to move in a circular orbit of radius R[SIZE="1"]M about earth. The period of the moon's orbit is 28 days. The radius of the orbit of a...

"Electric fields" reference What book would you recommend to study "Electric And Magnetic Fields" from ? Thanks.

I have a question that is confusing me perhaps one of you can help me. If I hook up a constant potential difference to a capacitor and place a dielectric inside of it, will the electric field decrease even if the plate separation remains constant? I think that the capacitance will increase as...

I'm confused as to how the concept that 'things' have a wavelength applies to an electromagnetic field, which has momentum, but not mass: what 'things' have wavelengths? Are there other criteria, other than whether something has mass or momentum, that must be fufilled before talking about...

I have a general question about dipoles. Doesn't the magnitude of the electric field attain its highest values in the vicinity of the midpoint of the distance between the positive and negative point charges? This is interesting, because if you consider only one point charge, then the magnitude...

A particular Gieger counter has a metal cylinder with an inner diameter of 2 cm along whose axis is stretched a wire with 44 N of tension. The potential difference between the wire and the cylinder is 890 volts. The wire has a length of 6 cm and an outer diameter of 1.5 X 10-4 cm. A. To find...

Problem: A solid coppper cube is placed in a constant Electric Field in x-direction. The faces of the cube are parallel to xy, yz, xz - plane and one corner is at the origin. Draw the field lines as they would be observed looking down on the cube towards the xy plane. Show at least two...

Here's my problem: Three 10-cm-long rods form an equilateral triangle. Two of the rods are charged to + 10 nC, the third to -10 nC. What is the electric field strength at the center of the triangle? Answer in back of book: 1.08 * 10^5 N/C By looking at the corresponding section, it...

Hi, Suppose we have a polarized object, and wish to calculate D(r) using D(r) = epsilon E + P Do we have to account for the electric field that the polarized object creates, or is it enough to just use the electric field which created the polarization? Thanks Ray