# Tagged Questions

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### Equation for magnetic field due to a current in straight wire [closed]

How can I derive the expression for the magnetic field due to a long straight current carrying wire using the Biot-Savart law? The final expression should be: ...
60 views

### Magnetic Shielding?

Can magnetic fields be "blocked"? For example, in the game, TitanFall, a robot stop bullets with ( presumably ) a magnetic shield. I wish to calculate the magnetic force required to stop a bullet ...
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### How does this particle behave in the magnetic field?

I have the above question and I have though about it every way and can't seem to find out. So what I have concluded (ignore the answers on the img) Is that the force is on the z axis because the ...
370 views

### Determining $y$ coordinate of charged particle motion [closed]

I've tried several different ways, with a tutor, and with other colleagues. One of my colleagues has even gone to the professor with whom he worked out an equation for the component, and it was later ...
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### Graph of Lorentz force in function of angle between v and B-field?

I need to draw a graph of the magnitude of the Lorentz force in function of the angle between the velocity and B. Am i right in supposing this will be a sine wave?
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### Calculting the magnetic field from rectangular conductor?

I want to apply the Biot-Savart law to calculate the magnetic field at a point created by current flowing through a square/rectangular conductor. More specifically, a trace on a printed circuit board. ...
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### Calculating repulsion due to eddy currents?

I have a conductive particle moving at a known speed through changing magnetic field (Permanent magnets attached to a rotating drum alternating north/south). These particles will have induced eddy ...
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### $\hat{\imath}$ component of force exerted on an electron by a magnetic field?

The magnetic field over a certain range is given by $\vec{B} = B_x\hat{\imath} + B_y\hat{\jmath}$, where $B_x= 4\: \mathrm{T}$ and $B_y= 2\: \mathrm{T}$. An electron moves into the field with a ...
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### Want to achieve maximum magnetic force & find out the max point [closed]

Hi Sir/ Madam Want to achieve maximum magnetic force & find out the max point for this setting, want to know is the strongest magnetic force must in the 'dot' area ( middle poin of setting ) ...
283 views

### Tesla to Newtons [closed]

Is it possible to convert Tesla to Newtons of force? Or magnetization force H:(A/m) to newtons?
339 views

### Current flowing through a square loop - Magnetic Field [closed]

A square conducting loop of wire of side $2a$ carries a uniform current I. Calculate the magnetic field at the centre of square due to the current in the loop.
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### Lorentzforce and righthand rule [closed]

Figure 1: A spool is hung on a spring. A part of the coil hangs in front of a homogeneous magnetic field. The coil is incorporated in an electrical circuit. See Figure 1. the coil ...
360 views

### Ampere's law on a long wire with varying current density [closed]

On a question from my book: A long straight wire with a circular cross section of radius $R$ carries a current $I$. Assume the current density is not constant over the cross section of the wire, ...
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### determining Induced emf/current through v x B . l

I am working on a question from my book. I am wondering how they conclude emf is negative in this case. looking at $$\mathcal{E} = \vec{v} \times \vec{B} \cdot \vec{dl}$$ If there's some implied ...
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### Flux increase due to velocity?

I have a book question I'm trying to understand: The first bit is easy enough. The second part I was confused so I checked the solution: B is into the page. The flux increases as the bar moves ...
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A long cylinder of radius $R$ is made from two different material. Its radius $r<r_0$ $(r_0<R)$ part is a material with superconducting transition temperature $T_1$, and its $r_0<r<R$ ...
203 views

### Lorentz Force Law and cycloid motion

The question I have is from Intro to Electrodynamics by Griffiths (Page 206, Example 5.2) http://imgur.com/a/sfBlt When using the initial conditions $y(0) = z(0) = 0$, I get: $y(0) = 0$ implies ...
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### Magnitude of magnetic field at the center of circular wire

I'm preparing for an exam by solving the sample questions , here is the one I'm having difficulty with : Following is the given circuit. Which contains two resistance $R_1$ and $R_2$ in form of ...
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### Energy spent by motor in a period

Consider a single coil that is turning in a constant and uniform magnetic field thanks to a motor. The normal to the coil is given by: $${\bf u}(t)=\sin (\omega t){\bf u_x}+\cos(\omega t){\bf u_z}$$ ...
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### Pressure experienced due to magnetic force?

A current $I$ flows in a long thin walled cylinder(parallel to the axis) of radius $R$. What pressure do the walls experience? This is the 263rd problem in Section III from the book 'Problems In ...
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### accelerated charged particles and interaction with magnetic field

In high school we are taught that magnetic field perpendicular to velocity of an charged particle experience perpendicular force that causes it to move in circular path by relation ...
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### How to find the direction of the magnetic field for an infinite conducting wire?

We've got two long straight wires carrying current of 5A and placed along x and y axis respectively current flows in direction of positive axes we have to find magnetic field at a) (1 m,1 m) b) (-1 ...
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### Quantum Cyclotron Frequency - Why is it off by a factor of 2?

Say you have a magnetic field $\vec{B}=(0,0,B_0)$. Then the Schrodinger Equation Hamiltonian for a spin-2 particle of charge $e$ moving in this field is: H = ...
137 views

### Current to cancel Earth's magnetic field

I'm making a lab report where I've used a Helmholtz coil and a magnet to find Earth's magnetic field intensity in the area by relating the frequency of oscillation of the magnet when a certain current ...
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### Magnetic force doesn't do work and therefore can't change the KE of a particle?

I am having a real hard time understanding the principles behind a question I've come across during test prep. Here is the question: Q: A proton and an electron are traveling in the uniform ...
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### Superconducting magnet

This is a somewhat more detailed question related to this one. The problem I want to solve is problem 1 here. What I tried: a) From $V=-L\frac{\mathrm{d} i}{\mathrm{d} t}$, we can integrate and ...
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### Finding the terminal velocity of a magnet dropped in a solenoid

We have to find proportionality of the terminal velocity with the factors of the system: Plot: a small dipole(mass $m$) with dipole moment $\mu$ is dropped in a long solenoid (radius $r$, ...
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### Superconducting diamagnetic sphere in uniform magnetic field

What is the size of the magnetic dipole moment $\vec m$ of a superconducting diamagnetic sphere $radius=R$ in a uniform magnetic field $\vec B_0$? Since there is no free current, we can solve for ...
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### Liquid benzene magnetic susceptibility

In a solid state physics problem, I'm asked to make a rough estimate of the contribution to the diamagnetic susceptibility of the outer electron of each carbon atom. The wavefunction of these ...
175 views

### Movement of the particle in a magnetic field

This is the numerical question. A particle having a mass of 0.05 mg carries a charge of $5\times10^{-6}C$. The particle is given an initial horizontal velocity of 5000 m/s, what is the magnitude ...
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### Equation of motion of charged particle under effect of magnetic field

A charged particle with specific charge q/m diverges from the origin [to the first quadrant] by angle X with x axis and with velocity v. To bring the particle back to the x axis, a magnetic field B is ...
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### If I have a rectangular loop moving through a magnetic field, which way will it go?

If I have a rectangular loop moving through a magnetic field, which way will it go? A uniform magnetic field (say it's pointing into the page) A square/rectangular loop of wire moving into the field ...
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### B-field and Magnetic forces, speed of a particle

Let's say I have a particle moving perpendicular to a uniform magnetic field of magnitude $x \ T$, and it moves in circle with a fixed radius. How do I find the speed of this electron? Initially I ...
1k views

### Magnetic Fields created by Current-Carrying Wires

The drawing shows two perpendicular, long, straight wires, both of which lie in the plane of the paper. The current in each of the wires is I = 5.6 A. What is the force and torque acting on each wire ...
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### Point where resulting magnetic field is equal to 0

I am trying to solve the following task Given 3 infinitely long current carrying wires, as shown on image ($I_1=I_2$ , $I_3=2I_1$) and $r=5 cm$ calculate the point between them (in the same plane; ...