Magnetism Definition and 974 Threads

Can someone explain this video: If I put this together myself should I expect it work or is that some hoax? If that's just a normal use of magnetism, then where can I read more about the principles behind it? Do these magnets get weaker over time?

Feel Free to give tips or answers to any or all of these questions Homework Statement 1. Two Point charges qa and qb are located on the x- axis at x=a and x=b on the graph of E the x-component of E. a) What are the signs of qa and qb? b)What is the ratio of|qa/qb|? c) Draw a graph of...

Homework Statement In a certain region, the Earth's magnetic field has a magnitude of 5.5 x 10-5 T and is directed north at an angle of 40° below the horizontal. An electrically charged bullet is fired north and 19° above the horizontal, with a speed of 700 m/s. The magnetic force on the...

May be a trivial question... The forces that arise from the magnetic field are Lorentz forces that not make mechanical work. When a piece of iron is attracted by a magnet is accelerated and its kinetic energy increases: Who does the work necessary?

Homework Statement A toroidal solenoid has a 60cm inner diameter and a 65cm outer diameter. The toroidal solenoid has 200 turns and carries a current of 30 Ampere. Determine the range of values for B inside the toroid. Homework Equations Ampere's law for toroid: B = Uo*N*I/2*pi*r where Uo =...

Homework Statement Calculate the potential energy, by ion, in an infinite bi-dimensional ionic crystal. Hint : Use the power series expansion of \ln (x+1). Homework Equations \ln (x+1)=\sum _{i=1}^{\infty} \frac{(-1)^{i+1}x^i}{i}. The Attempt at a Solution W=U=k\sum...

I'm confused as to wither or not magnetic fields do work. From reading the forums, as well as my textbook and online resources there seems to be conflicting answers. We talk about magnetic energy, and how work relates to change in energy but then I hear that magnetic fields do no work. Could...

If you fire energetic ionising particles, like electrons or protons, at a stationary target, the important interactions are ionisation, nuclear reactions and scattering. But if the incoming particles are traveling at high speed, will they not generate a high magnetic field? Why is such a...

Alright, so magnetism, this weird force that just seems to occur at the end of a lump of magnetic metal. I understand that: - The movement of electrons "facilitates the occurrence" of a force called magnetism - Magnetic materials have unpaired electrons in their shells which all have the same...

Are electricity and magnetism field lines the same? please be detailed!

Homework Statement Ok guys, this problem has a few steps to it, and id appreciate any help I can get. Ok, so beam of electrons moving left, positive particles with same but opposite charge moving right, both moving at 1x10^8 m/s. Then there is a proton moving left on top of the beam nearby...

I plan to use a automatic genset controller to protect/run a synchronous generator. This controller determines when to disconnect the starter by determining the generator frequency. I plan to connect the exitor regulator to the main breaker so when the main breaker trips the regulator is shut...

Hi, I have a couple of questions here: 1st, I never really understood how magnetism induces current, like how does magnetic fields just suddenly cause electrons to flow. Another question I have is on how transformers work (the electric device, not the robots). I looked at some explanations...

does the fact that a moving charge creates a magnetic field, and a moving magnet creates an electric current, imply that the two are related or inverses of each other? -Tom

I've seen in feynman and on the internet a derivation that the force on a negatively charged particle from neutral current carrying wire can be shown to be purely magnetostatic in one frame of reference and purely electrostatic in the other frame of reference using the length contraction. The...

I just saw an instructor of EEE (YouTube) talk about Cross Product. He gave an example of when cross products are used. Here's what he said. He drew a vertical arrow and said this is current. Then he drew a circular arrow around the vertical line and said it is B. Then he drew a smaller...

What if i was traveling in a car with an e- with me. W.r.t to a positive charge at rest , it would seem accelerating to me i.e. it would have a magnetic field but acc. to a person on the ground it would just have an electric field. If there were a car moving relative to me , the person would...

Have always wondered this so maybe I can get an answer here: when a large industrial electromagnet is switched off and the electricity-produced magnetism ceases, is there a small amount of residual magnetism in the uncharged electro-magnet? If so, does it dissipate according to a established...

Why is it that 2 wires carrying parallel current attract each other i think they should repeal imagine 2 wires carrying electrons to the left then the current is to the right, in the reference frame of the moving electrons it seems like the electrons on the other wire are not moving so the...

I need an explanation that relates the equation to what I learned about the dot product of two vectors being the magnitude of the parallelogram formed by the two vectors in 2D or similarly by the paralleliped formed by three vectors in 3D. I want to know for instance if the resultant is...

Please consider the following… Suppose you were on a space-walk at the International Space Station and you had two refrigerator magnets. And suppose you gently released one magnet so that it remained “stationary” in space. And suppose you threw the second magnet as hard as you could in the...

Homework Statement Two small objects, labeled 1 and 2 in the diagram (see link), are suspended in equilibrium from strings of length L. Each object has mass m and charge +Q. Assume that the strings have negligible mass and are insulating and electrically neutral. Express all algebraic...

Homework Statement Two long thin parallel wires 13.0 cm apart carry 25 A currents in the same direction. Determine the magnetic field at point P, 12.0 cm from one wire and 5.0 cm from the other. (Sorry I don't have a diagram, but this is essentially a triangle, with sides of 13 cm, 12...

Okay, I will be honest, this is a homework assignment. For that matter this is the last homework assignment which is very crucial to preparing for the final. But the problem is I have 2 more finals for which I need to study for. So if you can please help me out and give a detailed solution I...

Okay, I will be honest, this is a homework assignment. For that matter this is the last homework assignment which is very crucial to preparing for the final. But the problem is I have 2 more finals for which I need to study for. So if you can please help me out and give a detailed solution I...

Okay, I will be honest, this is a homework assignment. For that matter this is the last homework assignment which is very crucial to preparing for the final. But the problem is I have 2 more finals for which I need to study for. So if you can please help me out and give a detailed solution I...

A 1.0 E -6 F capacitor has a charge of 10.0 micro C. It is connected to a 1.0 H inductor at t = 0. Compare the potential energy of the capacitor to the potential energy of the inductor at t = 10s. Which energy is greater?

Homework Statement Two 1m long current carrying wires are separated by 0.05m. One carries 2A and one carries 3A. What is the magnitude of the mutual force between them? In what direction does the force act on each wire? Homework Equations The Attempt at a Solution I apologize for not...

Homework Statement This has a lot of parts, but I think I got the first few, or at least I'm on the right track. You have an inclined plane (30 degree angle, the ramp part is 3m) with a 1kg metal bar that is 2m long at the top (mu static = mu kinetic = 0.1). The sides of the plane are lined...

I read recently that magnetism plays an important role in cramming all that matter into a black hole. But how is it possible that magnetic force could escape a black hole, having an escape velocity higher than the speed of light, therefore an impossibility of matter(or energy) escaping?

My physics book says that the magnetic field is caused by moving electrical charges, acts only on charges with a motion vector perpendicular to itself, and the force it exerts on a charge is proportional to the velocity of the charge. How does the moving charge cause this force, which does not...

Help with magnetism- hall probes- difference between 3 types -URGENT Given 3 uncalibrated hall probes A, B, C, a solenoid of a known number of turns and length and a long straight wire. I have to discover which of 3 probes is a metal, a p-type semiconductor, and an n-type semiconductor.The...

I was reading Michio Kaku's book Prallel Worlds recently and I believe I saw it say that Maxwell's equations for electricity and magnetism become the same for electricity and magnetism when monopoles are introduced. My question is, if the equations become the same then why don't we say that...

Hey, first of all, I wanted to know that if you pass an electric current through an iron rod, for example, then what would be the relationship of it's electric field and magnetic field? Will they be parallel to each other or perpendicular?:confused: Second: suppose to fire a particle, let it...

Magnetism problem for General Physics 2! Homework Statement Suppose the rod in the figure has mass m= 0.40kg and length 20cm and the current through it is I= 40A . (Intro 1 figure) If the coefficient of static friction is us= 0.55, determine the minimum magnetic field (not...

Homework Statement The points A,B,C are the vertices of an equilateral triangle, of side L. Two equal positive charges q are at A and B. A)Find the electric potential at C assuming V=0 at infinity B) Give the expression for the work necessary to bring a positive charge Q from infinity to C...

Homework Statement Show the mathematical relationship between magnetism and electricity by looking at constants Homework Equations I have several equations but in don´t really know which one I have to use and I don´t see any big similarities except that there is force, charge, velocity...

Hello, The Lorentz force equation, F = q (E + v x B), is a complete description of the force on bodies arising from Magnetism and Electricity, right? So somehow it must be possible to get from the magnetism that exists in materials (like in a magnet) to this equation. I don't see how the...

Electricity and Magnetism questions...Gauss's law, grounding..etc. Alright so I am finally starting to understand the material, but I have a few questions. 1. An insulating spherical shell with an inner radius of 0.1cm and outer radius of 0.3 cm carries a total charge of 20nC. Use Gauss's law...

Homework Statement Find the net mag field at the points asked for. It is just a matter of getting the distances (r values) correct based on the points asked for relative for each wire. http://img4.imageshack.us/img4/5906/picf.th.jpg Homework Equations I think the relevant equation is: B =...

Homework Statement An electron moves at right angles to a magnetic field of .14T What is its speed if the force exerted on it is 8.7 X 10^-15 N? I am at a complete lossfor this question.

Hello, I am aware that magnetic forces can do no work. I am also aware that, in a conservative system, equations of motion that minimize the "action" (which are the true equations of motion) can be found with the euler-lagrange equation. The only information the euler-lagrange equation needs...

I need help understanding both of these terms. I know that diamagnetism is when the valence electrons of the material are paired and repel a magnetic field. Does that mean it repels like the North side of a magnet to another North side of a magnet? Or is it they don't attract at all...

Ok, I finished my physics I calculus based class, and really I don't feel like I learned a lot or mastered the material. I would spend many minutes nearing hours trying to think over my homework but with a load of other classes and the fact that we got all the hard and I do mean hard problems...

Homework Statement The question is as shown on the attachment. Homework Equations F = BIL The Attempt at a Solution To find the magnitude of the force I used the equation "F = BIL" and then I put in the values for each (B=0.25, I=15, L=0.20) and I got an answer (magnitude) of 0.75...

Homework Statement A 200-turn solenoid having a length of 25cm and a diameter of 10cm carries a current of 0.29A. Calculate the magnitude of the magnetic field B inside the solenoid. Homework Equations B = \mu0ni The Attempt at a Solution Well, I plugged the numbers into the...

Discovery challenges prevailing model! http://www.eurekalert.org/pub_releases/2008-10/nrao-ygm092908.php Astronomers have made the first direct measurement of the magnetic field in a young, distant galaxy, and the result is a big surprise. Looking at a faraway protogalaxy seen as it was...

I'm an IT person - non-scientist - but this problem has challenged me ever since high school physics: If two permanent magnets - pole to like pole - repel each other, the magnet suspended possesses potential energy. If a material can be found (that is non-magnetic and without any power...

Homework Statement Three plastic sheets that are large, parallel and uniformly charged are placed side-by-side. The electric field strength between sheets 1 and 2 is 2x105; the electric field strength between sheets 2 and 3 is 6x105. What is the ratio of the charge density on sheet 3 to that on...

What is magnetism?...preferably no links to other sites...just a conceptual answer...