Magnetic fields Definition and 644 Threads

Hi, I came to the following article, and I have a questions about it: http://galileo.phys.virginia.edu/classes/252/rel_el_mag.html From this article, it seems that if the electric current is not flowing in a wire, but instead in vacuum there will be no repelling force (since there is no...

Question A particle with mass 1.81 \times 10^{-3}\;{\rm kg} and a charge of 1.22 \times 10^{-8}\;{\rm C} has, at a given instant, a velocity \vec{v} = (3.00 \times 10^{4}\;{\rm m}/{\rm s})\hat{j}. What is the magnitude of the particle's acceleration produced by a uniform magnetic field...

Hello All, I was just rummaging through some old Tesla patents I have and I came across patent US381968, which describes different ways to make two-phase AC motors. The setup that I am interested in is on the second page and shows a toroidal core with four coils wrapped on it as the stator...

Hi, I want to know what the different methods out there to make a rotating field electrically. I am perticularly interested in the types that are produced by toroidally wound coils like the one here: http://upload.wikimedia.org/wikipedia/en/7/7a/RMFpatent.PNG but I want to know if it is...

I'm having trouble with 4 questions and not sure how to go about starting to solve them. If anyone can give me help on how to approach these questions, it'd be really appreciated. I just put them all down at once rather then making separate threads. Thank you. 1) An electrical transmission...

Hi all, In one of the books I'm reading, it says that shields are only used in the presence of alternating fields. However, in some websites, I see people using magnetic shields for permanent magnets which has a magnetostatic field. I ran some simulations, and the filed of a permanent magnet...

Okay, say I have a coiled conductor below where the direction of the magnetic field is indicated in the North direction. +()()()()()- ---> N If I were to place a compass in the following position, what would happen? (a) COMPASS +()()()()()- (b) +()()()()()- COMPASS Okay, so...

Hi; I am curious about the correspondence between the E&M fields and photons in Quantum Electrodynamics. I want to calculate the electric and magnetic fields produced by a single photon. This may look like a rather long post containing an elaborate question designed to stump everyone, but it...

question on electromagnetism, moving electrons with respect to other electrons causes a field to be felt right? maybe if i skip to my example itl make sence... lets say you fire a bullet parallel to a wire. will the bullet feel a magnetic field, and if so, will it change its tragectory...

The magnetic field lines emerge from the north poles to south poles.Why its always true this event? i expect your answers please... :confused:

I am wonder what produce the Earth's magnetic field .Can anyone tell me . Besides , I am doing a experiment to measure the horizontal component of Earth's magnetic field . I am using a copper (about 16 mm in length) and a power supply of two volt . I use the copper to create the solonoid but...

I'm trying to understand why, when, in a solenoid for example, electrical current is magnetically induced, doesn't the newly created magnetic field due to current "cancel out" the effects of the original changing magnetic field. One person I asked suggested resistance, and this sounds completely...

Hey guys I'm new here and needless to say I am completely lost... well here is the problem... What is the maximum current that a wire can carry if an experimenter is performing an experiment 0.60 m away that deals with the Earth's magnetic field (4.5*10-5 T), which she wishes to measure to...

I have a few questions on magnetic fields: . 1) If two magnetic fields are perpendicular, how do they act? . 2) If the fields are setup as shown in the diagram [see attachment] how do they act? . For #2 I see how it is setup, but I get confused by all the circling ad everything :confused...

What magnitude and direction would an electric field, E, need to be to cancel out the force on an electron traveling with speed, v, in magnetic field B? I know the formula for the force on an electron in a magnetic field is F=qvB. The formula for the force on an electron in a electric field...

A north pole and south pole are separated by some distance (positioned vertically). Using the discrete version of Ampere's law: Take a path rectangle with one vertical side completely inside the magnetic field and the other vertical side completely outside the magnetic field. Where h =...

The magnetic field around a magnet very much looks like the solution of a differential equation (which I guess it is, at least apprx). Now, can anyone give my a few simple exaples of such differential equations describing a magnetic field around a magnet?

Hi Can anyone tell me the differences between normal light (waves of the EM spectrum, i.e. visible light, gamma ray, radio waves, etc.) and magnetic field? I know that both, light and magnetic fields, consist of photons and i know that magnetic and electric fields are perpendicular to each...

In one of his lectures Richard Feynman describes the effect of a magnetic field on an electron. In doing this he describes the magnetic field as being made up of many photons. If a photon is an oscillating electromagnetic field how can it be just a magnetic field also ?

I would like to know what is the relationship between the Magnetic field strength and the flux in a toroidal coil of wire. I have an expression for the magnetic field strength at a distance r but need to know the flux through the coil. Any help is welcome.

a long wire is bent into a hairpin as showqn in the figure. If the wire carries a current of i = 1.5A a) what is the magnitude and the direction of B as point a? b) at point b very far from a? assume R = 5.2mm a) for a since R is constant s = 2 pi R B = \frac{\mu_{0} i}{2R} and this...

The north and south ends of two magnets are placed facing each other so that they create a uniform magnetic field. A small metal object passes through the field with a constant velocity. Sketch a graph to show how voltage varies with time for the path of the object from t=0 to t=3 t=0 object...

confused on Magnetic fields! Hello everyone, we just started a chapter on magentic fields due to currents and I'm pretty lost. I'm looking at the homework and its making no sense to me.. I read the section and yet its not helping either. It gives lots of formulas but doesn't really explain...

Anyone have any good references or insights on excitons; excitons in bilayer semiconductors; excitons in high magnetic fields (fractional quantum Hall regime) or Bose condensation of excitons ? I'm going through the literature but want to make sure there isn't something useful out there that...

A question concerning atoms in magnetic fields: Why does the LS-coupling break down in a strong magnetic field (Paschen-Back effect)? I have until now only gotten this stated as a fact, but if anyone could give a few arguments it would be appreciated. Why aren't the individual components of...

Hi a short question: can I use the superposition principle for magnetic fields? reegards tem

I ran across this article in "Newsweek-Next Frontiers" about stimulating neurons directly by firing large magnetic pulses to specific locations in the brain: Address: http://www.msnbc.msn.com/id/9557716/site/newsweek/ Well, I can imagine a much more "accurate" device which can affect...

can a faradays cage be used to block external magnetic fields from interfering with the contents of the cage?

Hey I'm wondering if someone can help me out with this question. Q: In order to measure the magnetic fields produced by the power lines carrying 50Hz alternating current, a coil consisting of 1500 turns of area 5cm^2 as constructed. Suppose that there is a single power line carrying a...

would increasing the speed at which magnet passes through a coil Increase,Reduce or does not change the amount of electromagnetic induction? cheers personally I would go with increase but want to see if I am right

Hello, I've just entered this forum and... the world of Physics. And I already have tremendous enigmas. Let's start with this. Oersted revealed that a static magnetic field exists in the nearby of a current loop. Now "current" means "moving electric charges" and e.m. theory states that a moving...

If a charged particle moves at a constant velocity in a straight line through a region of space, is the electric field and/or magnetic field in the region zero?

I don't understand this question at all- could someone please help- at least giving me a starting point- thanks A wire, of length 70cm is placed into a magnetic field of strength 0.001T. If the wire carries a current of 5 amps 1/ Calculate the magnitude of the forces on the wire if it is...

yes well i think i will get right to the point on this one, my first question is this i heard about these group of people that live neer the Hoover dam, specifically, neer the output power lines, that are complaining about electromagetic radiation from the powerlines, magnatisim. now my first...

Hey all I was just wondering if anyone knows how to figure out these two questions. 1) The difference in potential between the cathode and the anode of a spark plug is 1.0x10^4V. What energy does an electron give up as it passes between the electrodes? This one I am really pretty clueless...

i have a question that i need some help with: at time t1, an electron is sent along the positive direction of an x axis, through both an electric field E and a magnetic field B, with E directed parallel to the y axis. Figure 28-34 gives the y component Fnet, y of the net force of the...

"A magnetic field has a magnitude of 1.2 x 10-3 T, and an electric field has a magnitude of 5.1 x 10^3 N/C. Both fields point in the same direction. A positive 1.8 µC charge moves at a speed of 3.2 x 10^6 m/s in a direction that is perpendicular to both fields. Determine the magnitude of the net...

Please help me with magnetic fields - how can i find its direction?? The drawing shows two wires that carry the same current of I=85.0 A and are oriented perpendicular to the plane of the paper. The current in one wire is directed out of the paper, while the current in the other is directed...

I am trying to develop a model about how solar storms interact with the magnetosphere. In the picture attached, assuming that the magnets are fixed to their positions, how will the resulting magnetic field look like? Will the field lines of the larger magnet be deflected up and downwards...

I want to calculate the magnitude of a net magnetic field. I've got two long wires. One that carries a current of 6.2 A in the positive y direction and the other wire has a current of 4.5 A in the positive x direction. Is the resulting magnetic field the resulting vector when these fields are...

given that B = (6x, -9y, 3z) find the total force experienced by a rectangular loop in the z = 0 plane. 1<x<3 1<y<2 i used the torque equation, but my question is if i have to do the integration for all 4 sides of the rectangle. T = int(dl cross B)

Can anyone point me to some reference as to how magnetic fields are produced in the inter stella medium please.

Hi First, I´m new in this forum so I´m not sure if I´m posting in the right place. If I don´t...well, sorry. Then my question...I´ll try to explain. I´m playing with an inductively coupled RFID-reader and smart labels. Holding the smart label 90 degrees with respect to the antenna, the...

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...

A square coil and a rectangular coil are each made from the same length of wire. Each contains a single turn. The long sides of the rectangle are twice as long as the short sides. Find the ratio tsquare/trectangle of the maximum torques that these coils experience in the same magnetic field when...

Two oppositely charged objects exert a force of attraction of 8.0N on each other. What will be the new force of attraction if the objects are moved to a diustance four times their original distance of separation? i did this.. F=kq1*q2/4r 8.0N=9.0x10^9 (1)(1)/4r r=1.125x10^9m how can you...

help pls! since electrons cr8 a magnetic field due to their spin, shouldn't atoms be magnetic? o0

I desperately need help, for I am quite lost on this question: Consider the example of a positive charge moving in the xy plane with velocity v = cos(theta)x + sin(theta)y (i.e., at angle theta with respect to the x axis). If the local magnetic field is in the +z direction, what is the...

I been trying to work out these problems for the past two days but cannot come up with a solution. If anyone can help that would be greatly appreciated. 1) A 3.80-g bullet moves with a speed of 180m/s perpendicular to the Earth’s magnetic field of 5.00 X 10-5 T. If the bullet possesses a net...

Which one has more magnetic field Torus or Bolt when current is going though? :eek: