Electric fields Definition and 483 Threads

I have just read Feynman's QED book and am somewhat perplexed. I have read that photons are the culprit behind all electromagnetic phenomena. He explains electromagnetic radiation very well but I am lost when it comes to static fields. If two electrons are very close together (and repelling each...

Can anybody help me with this problem? Two small metallic spheres, each with a mass of .20g, are suspended as pendulums by light strings from a common point. They are given the same electric charge, and the two come to equilibrium when each string is at an angle of 5 degrees with the...

Hi; Could somebody please help me with the following question: Dry air will break down and generate a spark if the electric field exceeds about 2.90E+6 N/C. How much charge could be packed onto a green pea (diameter 0.800 cm) before the pea spontaneously discharges? The formula i used was...

Here's the problem: Can someone help me start it off? A long straight solenoid of cross-sectional area 6 cm^2 is wound with ten turns of wire per centimeter, and the windings carry a current of 0.25 A. A secondary winding of two turns encircles the solenoid. When the primary circuit is...

I'm having some trouble trying to derive an equation for the movement of a positive ion through a quadropole. The problem is that my primary source in this is "Physics for Scientists and Engineers with Modern Physics" by Raymond A. Serway and John W. Jewett, Jr. which has an excellent part on...

for the pentagon, there is a + charge at 1, - @2, - @3, + @4, - @5, and + @6. In part A, we are asled to find the net electric field at point P, which is half way between 1 and 2. Each side is 2 mm long, and each charge is an elemental charge. So, I did- E1=E2=kq/(r^2)...for r I used...

I have a nasty problem here which I have been working at for a while but keep getting rubbish answers. I have tried using: E = surface charge density/(dielectric constant * Epsilon0 (8.85*10^-12) but I get a dielectric material which has a lower dielectric constant than air. I really...

Suppose the light bulb in Figure 22.4b is a 60.0-W bulb with a resistance of 240 W. The magnetic field has a magnitude of 0.40 T, and the length of the rod is 0.60 m. The only resistance in the circuit is that due to the bulb. Minimally, how long would the rails on which the moving rod slides...

I'm working on these problems can anyone help me with it? 1. In an EM wave traveling west, the B field oscillates vertically and has a frequency of 56.0 kHz and an rms strangth of 7.90E-9 T. What is the rms strength of the electric field? 2. Pulsed lasers used for science and medicine...

Hi everyone, I just found this forum and am happy I did, being the only physics major in my physics 200 classes (community college :( ), I feel kind of isolated. Groups of people talking about computer science classes, engineering, and I'm alone, and my instructor/advisor still asks me...

1. An electron with a speed of 3.0 x 106 m/s moves into a uniform electric field of 1000 N/C. The field is parallel to the electron's motion. How far does the electron travel before it is brought to rest. I read the part of the text related to electric fields but I saw nothing that related...

I'm not sure if this has been asked, but i am in major need of help. i have 2 questions. first is determining the speed of a particle when the speed is parallel to the electric field. i talked to my prof. and he suggested finding the energy, U, and by integrating E with respect to z, by doing...

im not sure how to do this... An electron, starting from rest, is accelerated by a uniform electric field of 8.8×104 N/C that extends over a distance of 7.0 cm. Find the speed of the electron after it leaves the region of uniform electric field.

Hi, I am lazy so I am going to post two questions in the same thread. One of them, I think, has been posted before but I wasn't satisfied with the conclusions in the thread. 1. Suppose that electrical attraction, rather than gravity, were responsible for holding the Moon in orbit around the...

So here's the question: Two identical small insulating balls are suspended by separate 0.25m threads that are attached to a common point on the ceiling. Each ball has a mass of 8.0 x10^-4kg. Initially the balls are unchaged and hang straight down. They are then given identical positive...

Thank you for taking the time to review my work. I am posting problems with solutions, but I'm not sure if my solutions are correct. The problems are exactly how I have them written in front of me. These are mostly conceptual questions, which require a short answer of some sort. Q1. A...

Why is there no electric field inside a hollow cylinder? :confused: :confused: :confused: Thanks.

In a cyclotron, why do they not use electric fields to move them in circles?

I need help understanding electric fields. I basically suck at answering questions related to them (I get 95% of them wrong :cry:). What I do know about them is: The electric field vector moves from a positive charge (+q) to a negative charge (-q). (Is this the same case in a capacitor? I...

i have no idea how to do this problem: a velocity selector consists of electric and magnetic fields described by the expressions E=E(k hat) and B=B(j hat), with B=14.5 mT. Find the vale of E such that a 828-eV electron moving along the positive x-axis is undeflected. hmm..since it is...

I need some guidance if anyone can help me! 1. A small cube of volume 8.0 cm^3 is .30 cm from a metal sphere that has charge 2.00uC. If the cube is empty, what is the total flux through it? I tried finding the flux of the sphere as if it was a point charge but I don't know where to go...

1) In the first quadrant (x > 0, y > 0), the x-component of the net electric field is: always positive. always negative. sometimes positive and sometimes negative. 2) In the third quadrant (x < 0, y < 0), the x-component of the net electric field is: always positive. always...

Electric fields and electrostatic forces (1 question) I was wondering if someone can show me how to answer this problem. Thank you. 1)Two charges are placed on the x-axis, an unknown positive charge at x=0 cm and a negative 8.642e-6 C charge at 2.993 cm from the origin. Calculate the...

Hey guys. Im currently troubled with a physics theory that i can't explain, or prove. The question: Discuss whether it would be possible to design a similar train (Magnetic Levitated Train) by putting the electric field to use (and not using a magnetic field at all). So i have to see...

I am reading a book about general physics kinematics, optics, waves, etc. It focuses more on history than on explaining equations or sample problems. One of the sample problems in Electric Fields section asks to find energy and speed when a positron moves from one plate that has electric...

I need help with the following, I don’t even know how to start A molecule of DNA ( deoxyribonucleic acid) is 2.17μm long. The ends of the molecule become singly ionized – negative on one end, positive on the other. The helical molecule acts as a spring and compresses 1.00 % on becoming...

There are 4 equal charges of 2 micro Coulumbs in a shape of a square. 2 positives line up on 1 side, which is the left side and 2 negatives line up on the other side, which is the left. Again, the charges are of equal magnitude. The question asks for the magnitude of the electric field at the...

Hi, lately, me and my friend wanted to build a monorail. suspended by magnets, and powered by electricity. we can't manage to create propulson. The Question? What shape and how are electric fields formed? P.S. Please don't call me a simpleton, I'm only fifteen.

I'm having trouble with this question. Where am I going wrong? Three charges are at the corners of an equilateral trangle. The bottom left corner has a charge of 2.00e-6 C, bottom right -4.00e-6 C, and top with 7.00e-6 C and separated by 0.500m. Calculate the electric field at the...

Hello all, Physics is generally pretty hard for me, so understanding Electric forces has been a monster. I've done what I "know" how to do on the following problem, but I need some input from the professionals =) Thank you in advance. Two point charges, Q1 and Q2 are located a distance .20...

I am going to attach the question along with this post so that you guys can see the questions and the diagram and be able to help me in answering my question better. I found the ccharge on the inner sphere and it is -3.928e-9 and the charge on the outer sphere is 8.15698e-9. Now I have to...

I'm having a problem with one of my physics problems. A plastic ball of radius 5 cm is hanging from a string 2m away from a charged glass rod. The ball has been charged to -5.13 microCoulombs. If the electric force on the ball is 0.6672 milliNewtons in the horizontal direction, what is the...

I'm stumped by the following problem: A circular ring of fine wire carries a uniformly distributed positive charge, q. Find the magnitude and direction of the electric field at the center of the ring caused by just the charge on a portion of the ring subtending an angle [the] at the center...