Magnetic force Definition and 398 Threads

Homework Statement The problem is in the attached image. Homework Equations The Attempt at a Solution I used the third left hand rule (seen in one of the attached images) and pointed my thumb (direction of the current) downwards because the question states that the current flows...

I have read about how magnetism arises from electric interactions and relativity. But in that respect i don't see how perpendicular wires can exert magnetic forces on each other. The movement of the charges is perpendicular so length contraction does not occurr in the direction of the current...

Hello friends, A while back I raised the similar question regarding absolute nature of Magnetic force due to a current carrying wire on a moving charge. But supposedly I was shown to be incorrect. Since, Magnetic filed is a relativistic effect, then every magnetic force should be...

Homework Statement question - see image Homework Equations The Attempt at a Solution so I use the equation F = BIl F = 0.2 * 0.4 * 8 = 0.64 Surely I just divide it by the number of electrons (8*1028) to get the answer BUT this does not give the correct answer. The correct answer is D?

A charged particle is placed next to a current-carrying wire. The wire produces a magnetic field, but if the particle is at rest, the field exerts no force on it. However, in a different inertial reference frame moving at speed v parallel to the wire, the particle is seen to be in motion, and so...

Hi All, In an experiment I ran to determine the trend between distance and magnetic force (produced by an electromagnet) the result showed that the trend was either an inverse quartic or inverse quintic function. Such a result was unexpected as the trend is documented as being an inverse cubic...

I hope this isn't in the wrong forum, it's not a problem, just a conceptual question for physics 2. I have a few questions that I cannot find answer for in my physics book or online. 1) Why does moving a charge parallel to the magnetic field result in zero magnetic force? Is this quality...

Magnetic Force on Various Sides of Spinning Loop?? Homework Statement A horizontal uniform magnetic field of magnitude 0.4 T is oriented at an angle of = 65° relative to a line perpendicular to plane of a vertical, rectangular loop, as indicated in the figure. The loop has a height of 8 cm...

I have a homework question that I am having some trouble with. This is my first post - so be easy on me. Question: A weight-lifter is able to hold a barbell with a maximum total mass of 205 kg above his head. A physicist uses him to conduct a classroom demonstration, asking him to hold one...

Homework Statement A particle moves through a magnetic field. In which situation is the magnetic force nonzero? A. The charge is zero and the particle is moving perpendicular to the magnetic field. B. The charge is negative and the particle is moving in the direction of the magnetic field...

I was reading <crackpot link removed> and was wondering if the inverse cube law for magnetic force still applied for situations where the object being attracted isn't another magnet itself? E.g. if there is an electromagnet attracting an iron nut is the rule still inverse cube and not inverse...

Homework Statement The current in a wire consists of n electrons per unit volume moving with a velocity v. What is the effect on these electrons of the magnetic field set up by the current itself within the wire? What is the force on one electron at a distance r from the centre of the wire...

Homework Statement The problem is shown in the link below: http://postimage.org/image/do2b7xz0b/ Homework Equations Biot-Savart Law's and dF=Idl x B The Attempt at a Solution My attempt is really just a mess. I essentially want to break it up into 2 segments. (1) Being the...

Homework Statement Find the magnitude and direction of the magnetic force on a charged particle with charge -4nC and velocity \vec{v} = (2.5\times 10^{4}) \hat{i} + (1.1 \times 10^{4}) \hat{j} (m/s) if the magnetic field in the region is given by \vec{B} = (1.2\times...

hello, I was just thinking since a photon trajectory is affected by a magnetic force.then I would like to know how much force does it take to do just so.

Homework Statement r= 0.12m B = 0.0720T I = 21.0A Fm= 0.104 N [up] A magnetic force of 0.104 N [up] acts on a 12.0cm long wire that runs[N 10 degrees E] through a magnetic field of 0.0720 T. If the current in the wire is 21.0 A, then what is the direction of the magnetic field? This...

Here is the question: A very thin wire which follows a semicircular curve C of radius R,lies in the upper half of the x-y plane with its center atthe origin. There is a constant current I flowing counter clockwise, starting upward from the end of the wire on the positive x-axis and ending...

Hello Forum, it is well known that the magnetic force |F_mag|= q v B sin(theta) does no work on a moving charge particles, i.e. it does not increase or decrease its kinetic energy. It only changes its trajectory. However, in the examples of a U shaped wire loop with a movable metal bar...

An isolated segment of wire of length L=4.50 m carries a current of magnitude i=35.0 A at an angle theta=50.3 degrees with respect to a constant magnetic field with magnitude B= 6.70E-2 T. What is the magnitude of the magnetic force on the wire? a) 2.66 N b) 3.86 c) 5.60 N d) 8.12 N e) 11.8...

Hello. So: Why does magnetic force tend to increase magnetic energy? 1) Usually, forces go in the direction of energy minimums. Why in this case is the opposite? 2) What does it imply? What is that makes magnetism particular in some senses, for example this, for example its force function...

Hi, I am slightly confused by the formula for finding the force on a current carrying wire. It is given as F=BIL where F is force, B is the strength of the magnetic field and L is the length of the wire being acted upon. What I don't understand is why this formula doesn't factor in the distance...

Homework Statement For any loop that may have symmetry, the magnetic force in the center must always be 0? Ex. circles, rectangles?

Hi, I have some very basic question that I've been struggling to find the answer to and before I go and buy some magnets to do some test of my own I thought I'd ask here: Do two magnets of different strength repulse each other at the same strength, or does one repulse the other more...

I am considering a positive charged particle moving with the velocity v into the magnetic field field B making an angle theta with the magnetic field, so the magnetic force exerted on the charged particle is perpendicular to the plane of B and v. My question is-Why the speed of the charged...

Recently I was thinking random thoughts and thought to myself, if there was a windmill like wheel with powerful magnets on each blade, would it spin? Here is a poorly drawn picture to help explain myself: http://imageshack.us/photo/my-images/191/magneticwheel.png/ [WARNING -- a user has...

Homework Statement Imagine you have a magnet (Henceforth named MagX) which weighs .03lbs, and it is being continuously pushed by another magnet's polar likes (Henceforth named MagY) with a force of 3 PSI. Is it possible to find the peak velocity of MagX, assuming that MagY stays at a constant...

Hello when we study electromagnetic ,it is easy to find force of a magnetic field on particle witch has electric charge (for example electron and ...) but what is force of magnetic field on ferromagnetic materials? for example if we put a cube of soft iron with a*a*a dimentions near a...

Sorry for slightly disregarding the proper format but I'm really quite lost so I can abide by what is expected. However I will be detailed Question is: A particle with a mass of 6.64e-27 kg and a charge of +3.2e-19 C is accelerated from rest through a potential difference of 2.45e6 V. The...

Hi There I want To calculate magnetic force in Solenoid. I need to relation between Force and (tesla, weight iron, and ...) F== B*M* ... is anybody here can help me ?

Homework Statement a closed wire loop with current I is in a uniform magnetic field B show that the total magnetic force on the loop is zero Homework Equations The Attempt at a Solution everywhere that I've looked just states it without explaining why

according too: http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/wirfor.html#c1F=(u * I *I2)/(2pi *r ) i thought it would be inverse proportional to the square of the distance?! can this be right?

Magnetic force between two parallel hanging wires (solved) Homework Statement Two long, parallel wires hang by 4.00-cm-long cords from a common axis. The wires have a mass per unit length of 1.30×10−2 kg/m and carry the same current in opposite directions. What is the current in each wire...

A 1.0 kg copper rod rests on two horizontal rails 1.0 m apart and carries a current of 50 A from one rail to the other. The coefficient of static friction between rod and rails is 0.60. What are the (a) Magnitude and (b) Angle (relative to the vertical) of the smallest magnetic field that puts...

The figure shows a current i through a wire in a uniform magnetic field , as well as the magnetic force acting on the wire. The field is oriented so that the force is maximum. In what direction is the field? I have uploaded the figure, and the relevant equations. My reasoning: -L is in...

Homework Statement 1. There is a counterclockwise current I in a circular loop of wire situated in an external magnetic field directed out of the page as shown above. The effect of the forces that act on this current is to make the loop (A) expand in size (B) contract in size...

Homework Statement http://img710.imageshack.us/img710/9295/roachj.th.png Uploaded with ImageShack.us http://img146.imageshack.us/img146/6360/61565460.th.png Uploaded with ImageShack.usThe Attempt at a Solution The vertical conductors does nothing because their forces are only horizontal...

Homework Statement A strong magnet is placed under a horizontal conducting ring of radius r that carries current I as shown in the figure below. The magnetic field makes an angle θ with the vertical at the ring's location. (b) What is the direction of the resultant magnetic force on...

I have the problem that I want to calculate the force of a magnet acting on a ferrofluid. I know this is is difficult but I am trying to make some simulations of physical behavior on ferrofluids Consider a U-shaped magnet with ferrofluid between the two poles. The distance between the poles...

Homework Statement A high-voltage power lines carries a current of 110 A at a location where the Earth's magnetic field has a magnitude of .59 G and points to the north, 72 degrees below the horizontal. Find the direction and magnitude of the magnetic force exerted on a 250-m length of wire...

Homework Statement 1) A charge Q is placed in a uniform magnetic field of magnitude a that proceeds in the -z direction. Its displacement is given by r(t) = (at^2+bt, 2bt, a). a) Find v(t). c) Find the magnetic force exerted on the charge at time t=t'. d) Now the magnetic field at time t'...

Homework Statement See figure attached Homework Equations The Attempt at a Solution I've attempted to draw the magnetic fields resulting at the location of wire 4 due to wires 1, 2, 3. I denoted them as B4,1, as in the "The magnetic field at 4 as a result of 1". Are these...

Homework Statement suppose that mag field is B=kz \stackrel{^}{x} find force on a square loop(side a) lying in the yz plane and centers at origin, if it carries a current I flowing counter clock whne u look down x axis Homework Equations Fmag=I\int(dl x B) The Attempt at a Solution...

imagine a magnet on a table placed near a fixed solenoid. When the current in the solenoid is activated, the solenoid attracts the magnet performing work due to friction with the table. how to admit in this case that the magnetic force didn't perform work since apparently there is a force times...

Homework Statement A particle of mass M=2x10-25 kg, charge Q=8e, and velocity vector v=1.0x105 m/s j enters a uniform magnetic field of strength B=2.5 T. The magnetic firld vector B lies in the x-y plane at an angle of \alpha =70 degrees to the x-axis. What is the magnitude of this...

Homework Statement 24. A uniform magnetic field is in the positive z direction. A positively charged particle is moving in the positive x direction through the field. The net force on the particle can be made zero by applying an electric field in what direction? A. Positive y B. Negative y...

When an object, such as a lump of iron, is accelerated by a magnetic field, where does the extra kinetic energy come from? Does the object become colder, or is it demagnetized?

Homework Statement In Vermont the dip angle for the Earth's magnetic field(the angle the field lines make with the horizontal) is 74 degree and the component of the field parallel to the Earth's surface is 0.16G. If an electron is shot with a speed 10^6 m/s vertically upward there, how large...

Homework Statement A "q" charge particle is moving along +y axis with velocity V0 starting from Origin. A friction force is acting on the charge particle " f= -(alpha)V(Vector) ".A constant magnetic field of magnitude B0 acting along +Z axis. The mass of the particle is m. Find the x...

Hi. My question is how the Lorentz magnetic force F=q\vec{v}\times\vec{B} is derived? Is it due to magnetic moment of charged particles? If the moving charged particle does not have magnetic moment (due to spin, so the torque on the particle is zero) how the magnetic force changes its direction...

Hi We've just begun studying magnetic force in school. Our teacher told us to explore the possibility of a paradoxical situation as F=qBv From different inertial frames, the apparent force will be different, won't it ? Our teacher told us that Einstein's theory of relativity solved the...