Magnetic fields Definition and 674 Threads

Hi. I am having a little trouble grasping the concept of a magnetic field. My book doesn't explain it very well. I understand that any magnet has a magnetic field, which is the space around it in which other magnets are subject to a force due to the magnet. What I am having trouble with...

I am following the book 'Introduction to Electrodynamics' by Griffith. In that book,the magnetic field outside an infinite solenoid has been found as follows: First of all,it is proved that the magnetic field is along the axis. (I have no problems with that proof). Then,a rectangular loop is...

Homework Statement James Clerk Maxwell used an equipment to confirm the nature of the magnetic field around a long, straight conductor. he found that no matter how large the current through the wire, the disk did not rotate at all. a. explain how this device can be used to determine the...

Homework Statement A wire is bent into a square connected to the terminals of a 9 Volt battery. The wire is constructed of copper with diameter of 1 mm and is bent into a square with side length of 30 cm. If the battery has a mass of 50 g and internal resistance 0.1 Ω, what magnetic field...

Homework Statement Well I just want to make sure I am right on this one. The question is how to steal electricity by placing a coil near a power line that carries alternating current in which the current varies sinusoidally. A.) For a single wire how should the coil be oriented to induce the...

Can someone please explain in details the origin of magnetic fields. I mean, how do electric fields produce magnetic fields and how do magnetic fields produce electric fields and all the other details.

Homework Statement Sodium ions (Na+) move at 0.851 m/s through a bloodstream in the arm of a person standing near a large magnet. The magnetic field has a strength of 0.254 T and makes an angle of 51 degrees with the motion of sodium ions. The arm contains 100 cm^3 of blood with 3 x 10^20 Na+...

Homework Statement An electron is accelerated through 2400V from rest and then enters a region where there is a uniform 1.7 T magnetic field. What are (a) the maximum and (b) the minimum magnitudes of the magnetic force acting on this electron? Homework Equations F_{b}=q(v * B) The...

A proton travels with a speed of 3.00 x 10^6 m/s at an angle of 44.0° with the direction of a magnetic field of 0.730 T in the +y direction. (a) What are the magnitude of the magnetic force on the proton? (b) What is its acceleration? Ok for magnitude of force, I used F = qvB sinø...

Hey, I was just thinking about the simple concept that a moving electron produces a magnetic field at right angles to its travel... Now here's my question. Since we live in a relativistic universe, what is the charge moving with respect to in order to create the field? If we say the observer...

Homework Statement Two isotopes of carbon, carbon-12 and carbon-13, have masses of 19.93x10^-27 kg and 21.59x10^-27 kg, respectively. These two isotopes are singly ionized (+e) and each is given a speed of 6.667x10^5 m/s. The ions then enter the bending region of a mass spectrometer where the...

Homework Statement A circular loop of wire and a long, straight wire carry currents of I1 and I2 (see the drawing), where I2 = 5.2I1. The loop and the straight wire lie in the same plane. The net magnetic field at the center of the loop is zero. Find the distance H, expressing your answer in...

Homework Statement An electron is moving through a magnetic field whose magnitude is 9.10x10^-4 T. The electron experiences only a magnetic force and has an acceleration of magnitude 3.60x10^14 m/s^2. At a certain instant, it has a speed of 6.30x10^6 m/s. Determine the angle (less than 90°)...

Hi everyone. I'm stuck on a physics problem and it's gotten me pretty confused.. and I came here wondering if anyone can guide me without giving me the answer and allowing me to learn the material instead of just receiving the answer without a clue as how to do the problem. I'd greatly...

Homework Statement Not too difficult really, but I'm not understanding why two wires with identical currents running through them will move together. The question is, 'what happens when two parallel wires carry identical currents in oppsite directions?' But I don't understand what happens...

Sunspots are areas of intense magnetic fields. They are supposed to be hotter than the surface of the sun but are darker because of decreased convection with the interior of the sun. Is it possible for these fields to trap matter from the sun's core and magnetically confine it at enormous...

Hello, I am new to these forums. We are studying magnetic fields in my Physics class at the moment and I had a question which my teacher could not quite answer, so I decided to seek some outside help. Anyway, here it is: Given: Two electrons are moving in a straight line in the same direction...

I'm engaged in a project that requires a magnet that can attract from at least a foot away. I mistakenly thought that a larger pull force would also mean a larger field and wasted $15 on a hook magnet with 130lbs pull force but only attracts from abut 2 inches away. So what kind of magnet would...

Help! Given that B = (6x, -9y, 3z) find the total force experienced by a rectangular loop in the z = 0 plane: Loop defined as... 1<x<3 1<y<2 with 5 Amp current flowing COUNTERclockwise.

hi, i'm puzzled. if an observer stands next to a length of wire with a dc current in it, he will detect a circular magnetic field around the wire due to the movement of the electrons, but no electric field due to the cancellation of the electrons' and protons' electric fields. what...

In lab, we used a bar magnet and a device that can measure magnetic fields. We put the measuring device near the north part of the pole and it measured 9T. We did the same to the south, but it gave us 75T. I was expecting it to give somewhere around -9T, is that what is suppose to happen? We...

help! here's what i have. this does some what explain how magnetic fields were used to invent the telephone? I am not sure what else to put. "In 1977 Bell patented a telephone that uses an electromagnetic transmitter. This invention works similarly to the variable-resistance transmitter...

Question: 1. a) what is the force per meter on a wire carrying a 9.80-A current when perpendicular to a 0.80-T magnetic field? b) What if the angle between the wire and the field is 45°? For part a) I know that F = ILB, where I is the current, L is the length of the wire and B is the size of...

A single stationary electron's magnetic flux caused by it's spin gives it a north and south pole right? does that mean it's north pole would be attracted to the south pole of a hypothetical nearby stationary electron? how would this attractive force compare to it's electric force of...

A circular loop of wire and a long, straight wire carry currents of I1 and I2 (see the drawing), where I2 = 4.9I1. The loop and the straight wire lie in the same plane. The net magnetic field at the center of the loop is zero. Find the distance H, expressing your answer in terms of R, the radius...

I have just done an experiment of magnetic fields around electric current in straight wire by using the seach coil. I have 2 questions about this... (1)why is this necessary to ensure the search coil is at the same level as the wire? My anwser:If the seach coil is not at the same level as...

Hello All, I have another set of quick questions that may or may not have a quick answer :smile:. When a simple two-electrode spark gap discharges, what shape do the eclectic and magnetic fields take on? If I were to draw the electric and magnetic field vectors, would they be pointing...

Please help me if you can... question: Use the following quantities to calculate the magnetic field strength of the horseshoe magnet. Mass of coil: 20 grams current in coil: 2.0 amps length of bottom of coil: 10cm angle coil makes with vertical: 30 degrees Hint: Equate magnetic...

Plz help me if you can... Question: A compass needle is not always balanced parallel to the Earth's surface but one end may dip downward. explain. I know that the answer has something to do with the Earth's magnetic field...or may be even gravity. I've read in my physics textbook about the...

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.

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.