Magnetic fields Definition and 644 Threads

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...

[b]1. Homework Statement [/b An electron has a kinetic energy of 5.80 10-17 J. It moves on a circular path that is perpendicular to a uniform magnetic field of magnitude 5.10 10-5 T. Determine the radius of the path? I know KE = 1/2mv^2 Using KE = 1/2mv^2 and saying KE = 5.8 x...

Homework Statement Two circular loops of wire, each containing a single turn, have the same radius of 3.6 cm and a common center. The planes of the loops are perpendicular. Each carries a current of 2.0 A. What is the magnitude of the net magnetic field at the common center? I have been...

Homework Statement In the figure 29-49, four long straight wires are perpendicular to the page, and their cross sections form a square of edge length a = 20 cm. The currents are out of the page in wires 1 and 4 and into the page in wires 2 and 3, and each wire carries 19 A. What is the...

Hi everyone, long time lurker, first time poster. Can someone please clear this up for me? Two wires running parallel to each other. I think its just an algebraic addition of the usual B(r)=u_0i/2pir but instead of r, we are using D and d aslso i apologise for my formulae, if someone...

i have several questions which relate to a project i will be starting soon we all know the right hand rule and others, but does it apply to 2 particles interacting with each other? for example if 2 protons are moving towards each other -------+> <+--------- like that ^ will relativity affect...

What effect does a DC magnetic field probe have when submerged in salt water ? i.e. There is not an electrode..just a plastic insulator with calcium ions pulsing through it giving off a magnetic pulse submerged in salt water. Sodium ions are paramagnetic, so would these be attracted to the...

Pardon this completely naive question. I am wondering why there are net magnetic fields on the Sun. Isn't there an equal number of protons - hydrogen nuclei - to electrons? Is there a separation of protons and electrons in different parts of the Sun so that there can be net currents? or are...

Hey, So I have a few questions because I don't understand some of the theory behind magnetism in matter. First, I have studied electric fields in matter and it seems logical that dielectrics get attracted to regions with higher field, because they're polarized and this creates the usual...

Is there any physical meaning to the cross product of two magnetic fields e.g. two fields generated in two different current loops?

Homework Statement It is given that when a copper or aluminium bar is set in oscillation in a magnetic field eddy currents are produced inside the bar. Should it be necessary that the bar should be made of a non-magnetic substance such as copper, aluminium etc.? Can it be a ferromagnetic...

I know that when you cut magnetic field lines with a wire you get an electric current. I know that if the left side of your screen was a magnet with its south side facing the north side of an other magnet which is the right side of your screen, and a wire coming in from the top of your...

Is the statement below always true: Work done by a magnetic field is zero. If it is. How do magnets attract iron?

My teacher told us that a constant magnetic field cannot do work on a particle , it can only deflect a particle , But we also talked about cyclotron motion and if the particle is moving around in a circle then it is experiencing a force . is this true ?

Hi.. I have 2 questions ( simple once i assure you :D) in Electromagntics. 1) ""A 0.120 m long copper wire has mass of 9.02 g and is carrying a current of 5.10 A perpendicular to a uniform magnetic field. This apparatus is placed in a strong magnetic field and the wire is found to levitate...

I've been following the recent thread about work done by magnetic fields, and I'm more confused than ever. I have a few questions about the subject. I have phrased them as true/false statements. Consider Statement A: If an object X moves in any direction which is not perpendicular to some...

I am working on determining the mH needed to produce a 250 gauss (0.025 T) magnetic field by a flat coil in a 8 ohm audio circuit that is PC controlled with an NHC tone generator. I need some help to do so as the information that I am able to get online does not allow me to make the jump from...

HI, A question which arises to me is about magnetic fields of a wire or a permanent magnet, Are they continuous? or are discontinuous like what we draw them when We want to show them in a paper? If they are continuous then why we see discontinuous lines when we make a test by iron's...

Homework Statement A Hydrogen atom is subjected to a magnetic field strong enough to overwhelm the spin-orbit coupling. Into how many levels would the 2p level split? What would the spacing be in the terms of Bext, e, me, and \hbar Homework Equations I know that I have to use the gLande...

Hello, I am concerned at some of the studies which investigate cancer and DNA Damage to brain cells and such. http://www.sciencedaily.com/releases/2004/02/040219075606.htm Now I understand that there is a big hype around the radiation of cellphones potentially causing cancer. It's...

According to every textbook I know of, magnetic forces do no work (e.g. David Griffiths Pg. 207). Yet this problem causes this to be hard to believe: If I take two magnets, I can set them down on a table (with a little friction). I then slowly push them toward each other, then at some point...