Magnetic fields Definition and 644 Threads

Hi! I am new user to this forums and on the start I have one question: "If I increase the speed of the electrons, will the magnetic field strength of the electrons increase? Thank you.

hello I was hoping someone could tell me a way to show my children a way to see a magnetic field?they are playing with magnets and don't underststand the way i explained how they work . if i could show them they might start to understand ... thanks in advance for your reply

The magnetic fields of several planets in our solar system are from what I've read caused by electric currents - does anyone know what the electric currents are caused by?

Homework Statement The north end of a bar magnet is pushed downward toward a wire loop in the plane of the paper. In which direction is the induced current, and which way is the induced magnetic field? A. clockwise, into the paper B. clockwise, out of the paper C. counter-clockwise...

Magnetic Field on an incline This is what looks to be a fairly simple magnetic field problem, but I don't have much experience in relating velocities to electrical currents, so I'm a bit stuck. The problem as described is So my variables to my knowledge are I = unknown m = 0.19 kg B =...

I know high magnet fields can be dangerous to health. My questions are 1) at what point does a magnetic field become powerful enough to be actually cause problems with human health and 2) why exactly is it hazardous at high levels? Thank you for your time.

As described in this report, the limits on the strength of stable magnetic fields are due to the magnetic forces on the conducting elements that tend to tear them apart: Magnetic Radiation Shielding: An Idea Whose Time Has Returned? Geoffrey A. Landis "The limit to the mass required to...

Hello, I was wondering, how exactly do magnetic fields interact? Say if you have 2 permanent magnets, 1 perhaps of 0.3T and another of 0.5T and you let the N and S attract so they clamp together, would the resulting field of the combination have 0.5T on both ends (i.e. would the surplus...

Ok this may be a silly question, but I have trouble grasping the function of the inverse square law and how it relates to the intensity of a magnetic field. It seems to me that if we take the same calculations of I2 = (I1 * D1^2) / D2^2 we come up with different real world answers based on...

A charged particle of mass m and positive charge q moves in uniform electric and magnetic fields, E and B, both pointing in the z direction. The net force on the particle is F=q(E+v x B)*. Write down the equation of motion for the particle and resolve it into its 3 components. Solve the...

If you were to take a superheated iron ball (say a heavily scaled down version of the Earth's core) and set it in motion inside of a heated and ultra-pressurized plasma globe with another light hard coating ontop of it also set in motion, would that generate a magnetic field similar in shape to...

I have a cluster of magnetic sources around a volume and I need to know the real magnetic field in a point (namely x_0) inside the volume by measurements in another point x' in the surface of the volume. I'm getting mad

Hi, The following is the standard qualitative explanation of the duality between electric field and the magnetic field given in our textbooks: Let a long straight wire carry a constant current i. A charge kept at rest near it does not experience any force, implying the absence of electric...

I started asking this question after one of my students had trouble with a problem asking for the net force on a current loop in a homogeneous magnetic field (on my first day of TAing, no less!). A current loop in a magnetic field will experience a torque, but not a net force. I always assumed...

I just have some questions about this stuff... How can the nature of a material determine if it can be made into a magnet? Whats the field around a straight conducter look like? Whats the direction of the magnetic field of a soleniod? Whats the action of a relay? How are the...

Ok can anyone tell me how the nature of a material determine if it can be made into a magnet? Can anyone illistrate any ne of these to me - the field around a straight conductor - the magnetic field direction of a soleniod -the action of a relay how was the telephone developed...

The question is a bit disingenuous. My real question is: How powerful would a magnetic field need to be to emit photons that fall in the visible spectrum - if that even makes sense. I know that magnetic force and electrical force are the same force: electromagnetism is transmitted by photons...

Question solved!

Homework Statement A charged particle enters a uniform magnetic field and follows this circular path: http://img257.imageshack.us/img257/781/physsk4.png Questions: 1: Is it positively or negatively charged, or is it electrically inert? 2: Why? Homework Equations None. The...

Are there any materials out there that can reflect magnetic fields, or can a twisted channel be formed for them to follow?

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.