Magnetic field Definition and 1000 Threads

Homework Statement Homework Equations ##\oint \vec{H} \cdot d\vec{l} = I_{free,enclosed}## ##\vec{B} = \mu_0 (1+\chi _m)\vec{H}## The Attempt at a Solution I found the magnetic field inside to be ##\vec{B} = \mu_0 (1+\chi _m)\frac{Is}{2 \pi a^2} \phi##. But why can't I use the same equation...

Homework Statement A closed loop carries a current of 8.0 A in the counterclockwise direction. The radius of the outer arc is 0.6m and that of the inner arc is 0.40m. What is the magnetic field at P? Homework Equations F = ILxB F = qV x B R = outer radius r = inner radius The Attempt at a...

Homework Statement Is a current that produces a magnetic field always going to be either an electron or a proton?

Homework Statement A ball of mass m is attached to a rope of length L which has one end at the origin; the ball moves in a horizontal circle at constant speed v0 on a frictionless plane; the velocity is always at 90◦ to the rope. The ball has a charge q, and moves in a constant magnetic field...

Homework Statement Ions having equal charges but masses of M and 2M experience a constant electric field while they travel a fixed distance d and then enter a uniform magnetic field perpendicular to their path. If the heavier ions follow a circular arc of radius R, what is the radius of the arc...

Homework Statement An intensity current I descends down the z-axis from z = \infty to z = 0, where it spreads out in an isotropic way on the plane z = 0. Compute the magnetic field. Homework Equations The only relevant equation I can think of is Ampere's Law, \oint_\gamma \vec{B} \cdot...

Homework Statement Homework Equations F= q v x B The Attempt at a Solution [/B] I tried using the right hand rule to find the direction of the force and seeing if the particle curves that way or not but obviously that's wrong

Homework Statement Show that for the case of a general inhomogeneous magnetic field, $$\dot{\vec{v}}=\frac{e}{2mc} (\vec{v} \times \vec{B} - \vec{B} \times {v})$$ The attempt at a solution I think I am oversimplifying things. I used that, for an electron in a magnetic field, m \frac{d...

This question is regarding the magnetic field lines around two abutting alternating poles. Take two axially magnetised disc magnets and place them next to each other (like tangent circles), so on each side the adjacent or neighboring magnet is of the opposite pole. By sprinkling iron filings...

Homework Statement Loop of current ##I## sitting in the xy plane. Current goes in counter clockwise direction as seen from positive z axis. Find: a) the magnetic dipole moment b) the approximate magnetic field at points far from the origin c) show that, for points on the z axis, your answer is...

Homework Statement An electron is shot towards an infinitely long wire with high current flowing througuh it. Please, look at my "sketch" in the attachment. How will its trajectory be affected? What curve will it be? 2. The attempt at a solution I thought about circular motion, but the fact...

<<Mentor note: Moved from non-homework forum>> If a uniform magnetic field ##{\bf{B}}=B_{z}{\bf{\hat{z}}}## exists in a hollow cylinder (with the top and bottom open) with a radius ##R## and axis pointing in the ##z##-direction, then the vector potential...

Homework Statement A wire with radius R= .01 m carries a current with uniform density. At a distance r1 =1.25m from the wire, the magnetic field has a magnitude of 2.55 μT. Calculate the magnitude of the magnetic field r2=.0065m from the wire. Homework Equations B= (μ0I)/ 2πr The Attempt at...

Homework Statement A long copper rod 8 cm in diameter has an off-center cylindrical hole 4 cm in diameter down its full length. This conductor carries a current of 900 amps flowing in the direction “into the paper.” What is the direction, and strength in tesla, of the magnetic field at the...

In my simulation I have a wire with a fixed current flowing, I observed if I change the diameter of the wire the magnetic field (B) in a fixed point of the space also changes, is it correct?

Homework Statement Suppose a straight 1.90 mm diameter copper wire could just "float" horizontally in air because of the force due to the Earth's magnetic field [PLAIN]http://www.webassign.net/images/boldB.gif, which is horizontal, perpendicular to the wire, and of magnitude 4 ✕ 10-5 T. What...

Hello, i want to draw the vector field and see the difference between propagation of field inside the body (with permeability μ>>1) and vacuum (μ=1). For the picture above i used Ampere's law, ∇xB=J and it illustrates only situation in vacuum. How to implement a contribution for example of iron...

Teenager just curious to see possible ideas.

Homework Statement I have two related questions here. 1. A positive point charge is moving directly toward P. The magnetic field that the point charge produces at P is? 2. Two positive point charges move side by side in the same direction with the same velocity. What is the direction of the...

I have read a previous forum discussing the possibility of creating a stronger magnetic field on Mars using tidal forces by putting a larger moon in orbit around Mars. My question is how large of an object would it have to be compared to Mars and how distant would its orbit need to be from the...

Hi! I wonder if there was any experimental measurement of magnetic field produced by mechanically moving charges. In principle the equation is well known. (1) But is there any experimental proof of this equation? I know it can be reformulated into this. (2) My question is "Is there any...

Hi While studying the shielded wires, i noticed that the magnetic field of the inner conductor can penetrate the shield conductor (can be calculated in the region 3). However, the boundary condition of the magnetic field at the surface (between dielectric and perfect conductor) of a perfect...

Hi, While studying the coaxial cable, i noticed that the magnetic field of the inner conductor can pass through the hollow conductor (can be calculated in the region 3). However, the boundary condition of the magnetic field at the surface (between dielectric and perfect conductor) of a perfect...

Homework Statement We consider a sphere of radius R which carries a uniform surface charge density \sigma and spins with angular velocity \omega around a diameter. We use spherical coordinates (r, \theta, \phi) with origin at the centre of the sphere and the z-axis along the rotation axis...

Homework Statement Given the figure below[/B] I need to calculate the total magnetic force on the semicircle section of the conductor. Current is I, Radius is R, and the Magnetic Field is B. Homework Equations d\vec{F} = Id\vec{l} \times \vec{B}[/B] The Attempt at a Solution [/B] dl is...

Homework Statement Homework EquationsThe Attempt at a Solution I uploaded the problem which I want to solve. Getting a general expression for magnetic field created by plane is difficult, I solve it another method. X is still larger than W, we can think palne current as just a infinite wire...

Homework Statement A copper disc of radius 10 cm is situated in a uniform field of magnetic flux density 1.0 * 10-2 T with its plane perpendicular to the field. The disc is rotated about an axis through its centre parallel to the field at 3.0 * 103 rev min-1. Calculate the EMF between the rim...

What is emf in the coil? As far as I know about emf is that it is potential difference between two terminals of a source but what if it is induced in coil by changing flux linkage. What exactly happen when emf is induced?

1. The problem statement, A capacitor is there in free space consisting of 2 circular plates of radius ##r## separated by a distance ##z## which is a function of time. ##z(t) = z_0 + z_1 cos (\omega t)##; ##z_0(<<r)## and ##z_1(<z_0)## are constants. The separation ##z(t)## is varied in such a...

Hello friends, I am trying to find how calculate the magnetic field created by current loop considering that there is a some geometry of material that can enhance the magnetic field. I thought it can be solved by multipling by permeability μ but realized that the iron core changes the picture of...

Homework Statement For a lab we need the equation of the magnetic field strength produced by a solenoid a distance r away from it (outside of it). I tried looking online and couldn't find one that didn't involve a bunch of cross products or similar. Wonder if anyone knows the formula? I know...

Homework Statement The diagram shows a uniform magnetic flux density B in the plane of the paper. Q and R mark the points where two long, straight and parallel wires carry the same current, I, in the same direction and perpendicular to the paper. The line through QR is at right angles to the...

Homework Statement The diagram shows a rigid conducting wire loop connected to a 6.0 V battery through a 6.0 V, 3.0 W lamp. The circuit is standing on a top-pan balance. A uniform horizontal magnetic field of strength 50 mT acts at right angles to the straight top part of the conducting wire in...

Homework Statement As shown in Figure 1 below, a long, straight conducting wire is stretched horizontally directly above a magnetic compass, both of which are separated by distance d. When electrical current is not flowing through the wire, the compass needle points in a direction parallel with...

Homework Statement A current of 3 A flows down each of two long vertical wires, which are mounted side by side 5 cm apart. Show on a diagram the magnetic field pattern in a horizontal plane, indicating clearly the direction of the magnetic field at any point. What is the magnitude and direction...

Homework Statement Two thin coils of radius R = 3 cm are d = 13 cm apart and concentric with a common axis. Both coils contain 10 turns of wire with a conventional current of I = 3 amperes that runs counter-clockwise as viewed from the right side (see the figure). (a) What is the magnitude...

I was looking at the diagrams from the lhc of the path of particles and notice that the path of the particles always craved parabolically not traveled strat outward from the point of impact. Why does this happen explachely when the particles are traveling at near light speeds thank you ahead...

I don't understand why electron moves this way... e.g. A light object (crampled paper) going down until gets hit by the wind will go parallel (at least a few seconds) to the wind direction ... why not with electron?

Homework Statement E is the "right answer" Homework Equations B around a long wire = mu * I / [2 * pi * r] The Attempt at a SolutionOK. I know that the magnetic field lines will travel in a clockwise direction around the wire from the viewer's orientation with the current going away from...

Hi! My high school physics tells me using right hand grip rule to determine the direction of magnetic field induced by a current carrying wire, but I wonder whether I can deduce the direction merely from Maxwell's Equations? Suppose now we have a current density in cylindrical...

Homework Statement This is a question regarding Problem 7.11 in Griffiths Electromagnetism book, which considers a falling square loop of aluminum through a uniform magnetic field pointing into the page with only part of the loop in the field at t=0 (see picture below). To solve this...

I am trying to calculate the magnetic field generated by an ideal toroidal solenoid by using the integral of the Biot-Savart law. I do not intend to use Ampère's circuital law. Let ##I## be the intensity of the current flowing in each of the ##N## loops of the solenoid, which I will consider an...

<--Why electrons move up if the Magnetic field is Horizontal? at 0:14 <-- the Magnetic field is Horizontal but the electrons are also moving horizontally...

Homework Statement A magnetic field is made up of A) positive and negative charges. B) magnetic domains. C) flux lines. D) magnetic poles. Homework EquationsThe Attempt at a Solution I thought magnetic field is made up of.. nothing ? Or does it mean 'What does magnetic field produced...

Homework Statement A magnetic field is made up of A) positive and negative charges. B) magnetic domains. C) flux lines. D) magnetic poles. Homework EquationsThe Attempt at a Solution

I want to know how does distance affect the magnetic field of a permanent magnet. I have read about the inverse square law and how it could apply to magnetic fields over growing distances, but doing so, I read about monopoles, which is a new concept to me. So, for the time being, I would like a...

Hello PF's members I know a magnetic field doesn't work on charged particles if magnetic field being perpendicular to the velocity of the particles. also i know magnetic field doesn't work if a charged particle enters with right angle into the field. But suppose that a charged particle like...

Hi, A time-varying (sinusoidal) voltage source is applied to a parallel plate capacitor of length d. Then the E field will vary according to E(t) = V(t)/d. However, this suggests that, for any given time, the E field is constant with respect to spatial coordinates. Therefore, the curl of E is...

Hello, Short description: In my country's physics olympics, if a loop of wire is moved in a changing magnetic field, the time derivative of the area (while calculating emf with lenz law) is the velocity of the loop (as if we're taking the time derivative of the AREA SWEPT). This has became an...

how can a rectangular coil placed in uniform magnetic field have torque? Isn't torque the force on an object while its rotating? Will the coil rotate in a magnetic field? I don't understand.