Magnetic fields Definition and 674 Threads

Homework Statement An electric field points into the page and occupies a circular region of radius 1.0 m. There are no electric charges in the region, but there is a magnetic field forming closed loops pointing clockwise, as shown. The magnetic-field strength 50 cm from the center of the...

hey, does anyone of you know the reissner-nordström metric, if there is a magnetic field instead of the coulomb field of a charged gravitating body? i just need the formula, but i could not find it in the internet, maybe someone here knows it? sorry for my english, but i am german...

I have had a question pop up latley. Can magnetic fields be somehow shaped or manipulated in anyway? Instead of just their regular form of an oval could you direct it to a diffrent shape? Just asking.

Homework Statement Two very long fixed wires cross each other at right angles. They do not touch but are close to each other. Equal currents flow in each wire in the directions shown below. Indicated the locus of points where the net magnetic field is zero. (I2) ^ |...

Homework Statement Hey everyone, I'm studying for a final and have been having difficulty determining induced magnetic field and current direction. I have a document (link below) with 5 sample problems. I answered them all, and put my reasoning for the answers there in italics. Would...

Homework Statement A particle of charge q and mass m starts moving from the origin under the action of an electric field \vec{E}=Eo\hat{i} and magnetic field \vec{B}=Bo\hat{k}. Its velocity at (x,3,0) is 4\hat{i} + 3\hat{j}. What is the value of x? The Attempt at a Solution The force...

What happens when same magnetic poles (i.e., NN or SS) are next to each other for say an hour or more - will the magnetic fields of those magnets become weaker or stronger? What happens when different magnetic poles (i.e., NS or SN) are next to each other for say an hour or more - will the...

The dramatic lines of force of a magnetic field demonstrated by iron filings in so many introductory texts suggests a problem: A magnetic field is never something that has a process of forming; it is always complete with lines of force: it can change, increase, vanish as in an EM field but never...

Hi, To understand the difference between uniform magnetic fields and field gradients would it help to make comparisons between their effects on different particles? The posts on Stern-Gelach shed some light here. For instance, what effect would a homogeneous and an inhomogeneous magnetic field...

1. Homework Statement Here is the picture with the arrows representing Electric Fields. a. Can you find any test charges on the xy plane? Where? b. Where can you find a magnetic field? 2. Homework Equations No idea... Amperes Law? 3. The Attempt at a Solution I just...

Hi, I'm new here but been looking to you guys for solutions for a while now. However, I cannot find the kind of solution on here already, so I thought I'd put it out here. My main problem with physics is always just finding the formulas I need. If you can at least point me in the right...

Electric/magnetic field at point P in presence of dielectric/magnetic material. I want to confirm either the electric field at a point P in space in an \vec E_{ext} field with the presence of a dielectric material is the sum of the \vec E_{ext} and electric field \vec E_{p} from the...

Homework Statement The diagram below shows two circuits: a very long straight wire, and a single loop rectangle of dimensions a and b. The rectangle lies in a plane through the wire and is placed a distance c from the long wire as shown. The long straight wire carries a current of I...

Homework Statement an electron accelerated from rest through potential difference V1=0.868 kV enters the gap between two parallel plates having separation d = 21.9 mm and potential difference V2= 91.2 V. The lower plate is at the lower potential. Neglect fringing and assume that the electron's...

I am a self taught physics enthusiast with a frustrating conceptual problem; I have been unable to come up with a reasonable visual model connecting electric and magnetic fields. I first began visualizing electric fields as a spherical wave that expands into 3D space. This made since because...

Hi, So this question might be a little simple, or not. But I was wondering about the exact nature of magnetic fields. Now obviously magnetic fields work in a vacuum(due to the fact that it's not a perfect vacuum), but would a magnetic field exist in a theoretical perfect vacuum? Now I think...

Hi, I am wondering if anyone here has heard of or can explain this variation of the right hand rule: Most websites i see tells you to point thumb in direction of current and curl the fingers, and the direction of the magnetic field is the direction you're curling. But my professor uses a weird...

Homework Statement Hall measurements are made on a p-type semiconductor bar (X) μm wide and (Y) μm thick. The Hall contacts A and B are displaced (Z) μm with respect to each other in the direction of current flow of (I) mA. The voltage between A and B with a magnetic field of 10 kG (1kG =...

HI all, I have been trying to calculate the displacement of an electron when subjected electric and magnetic field, please see the pic below: I anticipate that the electron will form an ellipse shape. Basically I would like to know how to calculate the major and minor axis of the ellipse...

Homework Statement An electron, initially at rest, is accelerated through a potential diff of 15.0 kv. It is then allowed to circulate at right angles to a uniform magnetic field of strength 2.35 T. Calculate the electrons final speed before entering the magnetic field. Homework...

Let V_B be the rate of decrease of the magnetic fields \frac{dB}{dt} For the 3rd path: \oint E\cdot ds = -\frac{d\phi _B}{dt} = -\frac{{d\phi _B}_1 + {d\phi _B}_2}{dt} \phi _B_{(t)} = A_{(t)}B_{(t)} The area is constant, it's only the magnetic field that's changing: \phi _B_{(t)} =...

Homework Statement A rectangular loop of wire of size 5 cm x 15 cm is placed near a long straight wire with side CD at a distance of 5 cm from it, as shown in figure 6.29. What is the net force exetred on the loop (magnitude and direction)? How does your answer change if the current in the...

Homework Statement How could the copper wire be made to produce a field more like the field produced by the steel wire? Homework Equations The Attempt at a Solution

Hoping that one of you electrical wizards may be able to help me out! I have a 30A DC HP power supply and a 1000W stereo amp that I want to use create a 10mT static DC magnetic field superimposed on top of a 1 mT AC magnetic field. To generate the AC field I have a 1 uF snubber cap. in series...

Hi, Is there a link between how fast a planet rotates, and the strength of its magnetic field? Or is there any recent work on this? I know that neutron stars rotate very fast and have v strong magnetic fields, and the same with Jupiter Okay, so that's not much to go on, but... is...

Homework Statement I have a couple questions from my textbook that I was looking at when studying, and since there are no answers, I'm not sure whether what I'm thinking is right. 1. A charged particle is moving in a circle in a uniform magnetic field. A uniform electric field is suddenly...

Apologies for any vagueness or ignorance here (and lack of citations) but I remember reading that ferromagnetism arises from spin behavior of many electrons. So in a broader sense, are all magnetic fields arising from spin? I am trying to understand how magnetic fields can be viewed at the...

Homework Statement Just wondering if I were to plot the magnetic field strength as a function of time of an RC circuit if they would be related through the time constant in the current (I = Ioe^-t/RC)?

Homework Statement A 1.0 cm copper wire of diameter 0.10 cm carries a current of 50.0 A to the east. Suppose we apply to this wire a magnetic field that produces on it an upward force exactly equal in magnitude to the wire's weight, causing the wire to "levitate." What are the field's...

Homework Statement Two insulated wires cross at a 30 degree angle but do not make electrical contact. Each wire carries a 5.0 A current to the left through their respective wires. There are two points. One point lies between the bottom 150 degree angle, and the other lies between the right...

Homework Statement A wire comes in from in finity (left side) and forms a shape by going up a length A, over a length A and back down a length A.(forming three sides of a square that is attached to this infinite wire), then takes a turn and leaves the page opposite to the side it came in...

If one wire has current running through it to the right, and another wire below it has current running it through the left... Why would they repel each other?? Can someone explain mathematically/ using right hand rule?? Thanks

Homework Statement Two long straight wires are shown. Wire 1 has a current of 25A and lies 0.05 m away from point O. Wire 2 carries a current of 110 A and sits a distance of 0.25m away from point O as shown. (i) What is the direction and magnitude of the magnetic field at point O due...

Do clocks tick at different rates in different magnetic fields .

This might sound crazy , but could a magnetic field exchange gravitons with something else , or can a magnetic field emit gravitons , And when a photon is emitted from the B field is the gravitational field from the B field transferred to the photon and then carried away by the photon .

Homework Statement I'm so confused about how to use the right hand rule..there are so many different sources telling me different things...like i need to use the RHR to like find the direction of the magnetic field using the current (and nothing else)..like i followed my book, and they said to...

Hello guys, Ok I read that light is an electro magnetic wave, but I don't understand what an electro magnetic wave is? I read wiki and seen diagrams but I don't get it. What do they mean light has an electric component, do they mean light is charged particles travelling, why does electric...

I would think that the strength of two different magnets can create a focusing effect where they overlap most strongly, however I'm wondering why we can't extend these fields to distant focal points in the same fashion as a laser (or maybe more where many lasers converge on a point, creating a...

A proton resistor spring system in a magnetic field going out of the page has a mass of proton 1.67*10^-27 kg, a spring constant k=500 N/m and the resistor has r=5Ω. The magnetic field strength is 0.8T. a) When released from rest, calculate the maximum displacement. b) What is the net magnetic...

Homework Statement An electron has a velocity of 1.2 * 10^4 m/s ( in the positive x direction ), and an acceleration of 2 * 10 ^ 12 m/s^2 ( in the positive z direction ) in a uniform electric and magnetic field. If the electric field has a magnitude of 20 N/C ( in the positive z direction)...

Proton Beam therapy is an advanced technique to destroy tumors by concentrating a high energy beam of protons to a specific depth inside the body of a patient. These proton beams are produced by accelerators and steered to the patient-treatment rooms by magnets. In a particular cancer treatment...

Reviewing basics of electrical theory [right hand rule; Faraday's law; etc.]. Come to surprising conclusion: If a number of wires are arranged like the spokes of an old fashioned wagon wheel and current flows through these wires towards the center, a magnetic field is generated which is the...

Homework Statement A velocity selector consists of electric and magnetic fields described by the expressions vector E = E k-hat and vector B = B j-hat, with B = 0.0130 T. Find the value of E such that a 830 -eV electron moving along the negative x-axis is undeflected? Homework Equations...

I remember learning in Electrodynamics last year that magnetic fields don't actually do any work. I don't seem to remember any of the explanation behind that. Can anyone explain why magnetic fields do no work (ie. How they differ from electric and gravitational fields). Thanks!

Homework Statement suppose a bar magnet is brought near a magnetic needle in a way that does not disturb the latter's position in the magnetic meridian. What can be said concerning the direction of the field due to the magnet? 2. Would reversing the position of the magnet has any effects on...

Here's a new and interesting design for a nuclear reactor which I've never seen before: http://www.rbsp.info/rbs/RbS/PDF/aiaa05.pdf It's harvesting the kinetic energy of fission fragments via magnetic fields, converting it directly into electrical energy. They say that past obstacles over...

If an electric field causes 2 previously stationary charges to accelerate(let's say that there was something inhibiting their movement that has now been removed) toward or away from one another, what type of field is between them, electric or magnetic?

Homework Statement A particle with a charge of −2.50×10-8 C is moving with an instantaneous velocity of magnitude 40.0 km/sec in the xy-plane at an angle of 50.0° counterclockwise from the +x axis. 1) What is the magnitude of the force exerted on this particle by a magnetic field with...

Suppose we are looking at the cross-section of a cylindrical current-carrying wire. Due to the motion of the electrons in the wire, it can be said that at all points at the surface of the wire a magnetic field tangential to the wire exists. Since there are electrons moving in that region as...

Suppose we have a current-carrying wire and an electric charge which is moving parallel to the wire with the same speed and direction as the electrons in the wire. The wire produces a magnetic field which acts upon the charge through a force. From the charge's reference frame, though, no...