# What is Uniform magnetic field: Definition and 101 Discussions

In physics, circular motion is a movement of an object along the circumference of a circle or rotation along a circular path. It can be uniform, with constant angular rate of rotation and constant speed, or non-uniform with a changing rate of rotation. The rotation around a fixed axis of a three-dimensional body involves circular motion of its parts. The equations of motion describe the movement of the center of mass of a body. In circular motion, the distance between the body and a fixed point on the surface remains the same.
Examples of circular motion include: an artificial satellite orbiting the Earth at a constant height, a ceiling fan's blades rotating around a hub, a stone which is tied to a rope and is being swung in circles, a car turning through a curve in a race track, an electron moving perpendicular to a uniform magnetic field, and a gear turning inside a mechanism.
Since the object's velocity vector is constantly changing direction, the moving object is undergoing acceleration by a centripetal force in the direction of the center of rotation. Without this acceleration, the object would move in a straight line, according to Newton's laws of motion.

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1. ### A diamagnetic sphere in a uniform magnetic field

Problem: Solution part a) where formula 6.14 is just M x n. We need to do part b without seperation of variables, I'm quite stuck. Will B just be the magnetic field inside a solenoid? How can I find the other fields.
2. ### Velocity of a relativistic particle in a uniform magnetic field

d(ɣmv)/dt = qvB (dɣ/dt)mv + ɣm(dv/dt) = qvB Substituting gamma in and using the chain rule, it ends up simplifying to the following: ɣ^3*m(dv/dt) = qvB Now, I am confused on how to solve for v.
3. ### Relativistic particle in uniform magnetic field (solution check)

My solution was as follows: $$\frac {d\overrightarrow p} {dt}=q \frac {\overrightarrow v} {c}\times \overrightarrow B_0$$ The movement is in the ##[yz]## plane so ##|\overrightarrow v\times \overrightarrow B_0|=vB_0##, therefore: $$\biggr |\frac {dp} {dt}\biggr |= \frac {qvB_0} {c}.$$ On the...
4. ### B Entangled protons in a uniform magnetic field?

In NMR, protons that are near each other exchange energy with each other by photon emission and absorption. Proton A is spin down, and proton B is spin up. proton A emits a photon and becomes spin up, and proton B absorbs this photon and becomes spin down. have the two protons been entangled?
5. ### Induced current in a coil from a constant uniform magnetic field?

Assume a solenoid coil(made up of ##N## windings) placed in the horizontal(##\hat{y}##) direction and in a constant uniform magnetic field. Would an induced current run through the(closed) coil if it spins around its central horizontal ##\hat{y}## axis? My guess is "no", since such a current is...
6. ### Law of motion for orbiting particle in a uniform magnetic field.

Hi all, I interested in how can I get low of motion in for orbiting particle in a uniform magnetic field $$\frac{d\vec{r}}{dt} = \vec{\omega}\times\vec{r},\qquad \vec{\omega} = \frac{e\vec{B}}{mc},$$ Of course, rotating about z' axis is very simple. \label{eq:K}...
7. ### Length of sides of a wire loop in a uniform magnetic field

If ##\tau= 0.0727, N=60, i=1.3, B=1.0,## and ##\theta=15##, I tried the following calculation: ##\tau=NIABsin\theta## ##\tau=NIs^2Bsin\theta## ##s^2=\frac {\tau} {NIBsin\theta}=\frac {.0727} {60*1.3*1*sin(15)}=0.0632 m=6.32 cm## The answer is probably right in front of me, but I don't know what...
8. ### Will EMF be induced in a coil that is accelerating in a uniform magnetic field?

My answer will be no for both (a) and (b) because there is no change in magnetic flux experienced by the circular coil. Am I correct? Thanks
9. ### Torque on a rectangular coil in a uniform magnetic field

So this was a section taken out from a question which I am trying to do shown below I have drawn a sketch to help me visualise of what is going on I have used Fleming's left hand rule to help me determine what direction the force is facing on each side of the coil. For the last part in...
10. ### Moving Electrons in a Uniform Magnetic Field

a) We can solve for acceleration by looking at FNETy FNETy = FE (G is negligible) FNETy = m * a The mass (m) of an electron is 9.1093836 x 10-31 kg. The elementary charge (q) of an electron is -1.60217662 x 10-19 C a = ε * q / m a = (4.0 x 102 N/C * 1.6022 x 10-19 C) / 9.1094 x...
11. ### Eigenstates of a free electron in a uniform magnetic field

I started with the first of the relevant equations, replacing the p with the operator -iħ∇ and expanding the squared term to yield: H = (-ħ^2 / 2m)∇^2 + (iqħ/m)A·∇ + (q^2 / 2m)A^2 + qV But since A = (1/2)B x r (iqħ/m)A·∇ = (iqħ / 2m)(r x ∇)·B = -(q / 2m)L·B = -(qB_0 / 2m)L_z and A^2 =...
12. ### Motion of a particle in a uniform magnetic field

All i could think is that the z component of velocity will remain unchnged as there is no force in that direction.And for the x and y component can we imagine the helical motion as a superposition of a circle and a straight line.So for x and y component can we solve for a particle moving in a...
13. ### Static free charge in a time varying infinite uniform magnetic field

Hello, Let's imagine we have an infinite plane (or large enough compared to the region of interest and measurements) pierced in normal direction by magnetic field B which is uniformly distributed but time varying. For the sake of simplicity we'll presume the magnetic induction is linearly (and...
14. ### EMF induced in rotating rod inside uniform magnetic field

Homework Statement A 40 cm rod is rotated about its centre inside a region of uniform magnetic field of 6.4 T. Given that the speed of rotation is 15 rad/s, find potential difference between the centre and either end of the rod Homework Equations emf = - ΔΦ / Δt ω = 2π / T The Attempt at a...
15. ### Path of a conducting sphere through a uniform magnetic field

Hello, could someone help answer this question for me: How would the path of a conducting sphere (i.e. AL) be affected as it passes through a strong uniform magnetic field orthogonal to the direction of motion. I believe the Lenz effect/Eddy currents will create a magnetic field opposing the...
16. ### The right hand rule in a magnetic field

Homework Statement An electron moving in the -z direction enters a region that has a uniform magnetic field in the +y direction. When the electron enters this region, what direction will it be deflected in? Homework Equations F=qv X B The Attempt at a Solution I tried answering this question...
17. ### Flux in a Uniform Magnetic Field

Thank you for reading my post. I was thinking about induced emf and magnetic flux and I realized I have a huge misunderstanding, but I don't know exactly what it is. Below I will list 4 statements which I logically know cannot all be simultaneously true. Can you please tell me which one(s) are...
18. ### Forces on magnets in a uniform magnetic field

If you have uniform magnetic field, would something like a halbach array which has a non symmetrical magnetic field experience a net force? If not, is there any way to shield one side of a magnet so that it would experience a net force? On a similar note, if you wound a wire around a sphere in...
19. ### I Will a uniform magnetic field be considered as measurment?

Any pure state of spin-1/2 particle can be represented by a superposition of spin up and spin-down relative to an arbitrarily direction. lw>=a l+> + b l-> where a^2+b^2=1 If there is no magnetic field, the measurement of the spin is random and we get 50-50 chance to be spin up and spin down...
20. ### Electrictric field due to changing uniform magnetic field

How does look like electric field lines due to change of the uniform magnetic field? Suppose we have a magnetic field between two infunite plates with surface current $i$ which is lineary change with time. Then B-filel is (x - perpendicular to plates, z and y along plates) B_z =...
21. ### Help with 3axis Helmholtz Coil

First of all, hello to all of you. My question is, I want to simulate 3-axis Helholtz Coil in Maxwell 3d. I made some models of it, but I am not sure I got all right - especially ration of coils in x-y-z and their current excitation. Second, i'd like to see H field, or B field plot if some of...
22. ### Net force on a Halbach Array in a uniform magnetic field

I have been unable to determine whether a Halbach Array of permanent magnets would experience a net force in a uniform magnetic field.
23. ### Torque in uniform magnetic field

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.
24. ### A Charged Particle moving in Uniform Magnetic Field

Homework Statement Problem given in the image attached. Uniform Magnetic Field : B Positive Charge : q Uniform Velocity : v Mass : m Charged particle enters the magnetic field making an angle θ with the plane perpendicular to the magnetic field. Width of the region of Magnetic field : d d <...
25. ### Proving Uniform Magnetic Field with Saddle Coils

Homework Statement We have seen that a long solenoid produces a uniform magnetic field directed along the axis of a cylindrical region. However, to produce a uniform magnetic field directed parallel to a diameter of a cylindrical region, one can use saddle coils. The loops are wrapped over a...
26. ### Induction heating by AC magnetic field-magnetic hyperthermia

Hi, I want to heat magnetic nanoparticles in an AC magnetic field. I need a uniform and a magnetic field about 15- 25 mT ) . I have thought about some designs, can you tell me which one is the most suitable design for creating a uniform alternating magnetic field? I need this system for...
27. ### Torque of charged rotating disc in uniform magnetic field

Hi, I'm having an issue with finding a starting point for the following problem. I've looked through my magnetism and electrodynamic notes but was unable to find a starting point. Could someone please help direct me on the correct path? Thank you. Homework Statement A thin circular disc of...
28. ### Particle in a uniform magnetic field

Homework Statement A particle with charge q and kinetic energy K travels in a uniform magnetic field of magnitude B. If the particle moves in a circular path of radius R, find expressions for speed, v, and mass, m.. (Use any variable or symbol stated above as necessary.) Homework Equations...
29. ### Can current be induced in a uniform magnetic field?

Currently doing my A2 Levels and have just been revising over electromagnetic induction. The general consensus seems to be that current can only be induced in a changing magnetic flux.The textbook I'm using constantly refers to cutting a magnetic field, i.e. moving a wire relative to a field, to...
30. ### An electron moving through a uniform magnetic field

Homework Statement An electron moves through a uniform magnetic field given by B = Bx i + (3.68 Bx) j . At a particular instant, the electron has velocity v = (1.88 i +4.86 j) m/s and the magnetic force acting on it is (2.43 × 10-19) N. Find Bx. Givens B = [Bx i + (3.68 Bx)] v = (1.88 +...
31. ### Electron moving through uniform magnetic field

Homework Statement An electron is fired at 4.0 x 10^6 m/s horizontally between the parallel plates, as shown, starting at the negative plate. The electron deflects downwards and strikes the bottom plate. The magnitude of the electric field between the plates is 4.0 x 10^2 N/C. The separation...
32. ### Circular loop with uniform magnetic field

Homework Statement A current carrying wire is bent into a circular loop with radius R and lies in the XY plane. A uniform magnetic field in the +z direction exists through out the plane of the loop. What is the magnetic force exerted on the loop? Homework Equations Fb = I lb sin (theta) The...
33. ### Electron enters uniform magnetic field and takes circular path

Homework Statement A time t = 0 an electron enters a region of uniform magnetic field B = 0.010 T and has kinetic energy of 6.40E-16 J. It goes through a half-circle, exits the field and then accelerates across a gap with a potential difference of 2000 V, increasing in speed. It then hits a...
34. ### Finding velocity of particles in a uniform magnetic field

Homework Statement Given are a uniform electric field, E = 30,000 V/m inside a capacitor (see picture), and a uniform magnetic filed, B = 10 T, perpendicular to the plane of the page, present in all of the area. Identical charged particles are moving in a trajectory marked by the dashed...
35. ### Uniform magnetic field and electric field

Homework Statement How would you find the period of a charged particle in an uniform electric and magnetic field? The charged particle has velocity that is perpendicular to the magnetic and electric field (which are directed in the x-axis). Homework Equations F=q(E+vxB) The Attempt...
36. ### Conducting bar in a uniform magnetic field

I'm studying for the MCAT and this problem came up. The correct answer is D. However the explanation was very confusing. The explanation is verbatim: " Let's start by considering A. Using the right-hand rule on a current running through the wire in figure 2 shows you that the rod is pushed...
37. ### Free Charge Moving in Uniform Magnetic Field

Homework Statement The drawing shows a particle carrying a positive charge +q at the origin (of x and y axis), as well as a target location located in the lower left quadrant. The target is just as far from the x-axis as it is from the y axis. There is also a uniform magnetic field...
38. ### Finding v of a charged particle in a uniform magnetic field

Homework Statement So there's a rectangular region in the xy plane subjected to a magnetic field B with strength 0.06T pointing in the -z. A proton moving in the xy plane enters the region with velocity v such that the velocity components are initially vx = v*cos(24), vy = v*sin(24). It...
39. ### Drift velocity in uniform magnetic field near charged wire

Problem (a) Derive and expression (using cylindrical coordinates) for the drift velocity of a particle of mass m and charge q in a uniform vertical magnetic field B\hat{z} when the particle is located at a perpindicular distance p from a long, straight vertical wire carrying a line charge...
40. ### Electrons in uniform magnetic field.

Hello. So I was wondering that when you shoot an electron through an uniform magnetic field, obviously Lorenz force starts to skew the path to that corkscrew shape that we all know. But then there is an acceleration towards the center of the circle, and if the the velocity of the electron...
41. ### Spherical capacitor in a uniform magnetic field

Homework Statement Two concentric spherical shells carrying uniformly distributed charges +Q and -Q at radii a and b, respectively (b>a). Now, they are immersed in a uniform magnetic field pointing along the z-axis. Find the angular momentum of the fields.Homework Equations No need. (I know...
42. ### Relationship of W and v in a region of uniform magnetic field

Homework Statement https://dl.dropbox.com/u/63664351/Physics/Electromagnetic%20Induction.PNG https://dl.dropbox.com/u/63664351/Physics/Electromagnetic%20Induction%20Answers.PNG Homework Equations W=mas. Unknown relation between W v and BThe Attempt at a Solution dW = m a ds = m dv/dt ds dW/dv...
43. ### Decaying particle in uniform magnetic field; what was the rest mass?

Homework Statement An unstable particle, initially at rest, decays into a pro- ton (rest energy 938.3 MeV) and a negative pion (rest energy 139.5 MeV). A uniform magnetic ﬁeld of 0.250 T exists perpendicular to the velocities of the cre- ated particles. The radius of curvature of each...
44. ### True or false? a conductor through a uniform magnetic field produces NO emf

Many sources on the web claim that when moving a conductor through a magnetic field, an emf is produced. However, some sources claim, that the intensity of the magnetic field also needs to change in order to produce a voltage over the conductor, for example...
45. ### Force on a Wire In Uniform Magnetic Field

Homework Statement A long wire lying along the x-axis carries a current of 2.60 A in the +x direction. There is a uniform magnetic field present, given by B=0.003i + 0.004j + 0.002k, where i, j, k are the unit vectors along the cartesian coordinate axes') in units of Tesla. Calculate the...
46. ### Disk in uniform magnetic field.

Homework Statement A cilindrical copper disk (radius R, thickness a) at time t=0 is spinning around its axis with angular speed w in a uniform magnetic field B parallel to its axis. The edge of the disk is connected to the center with a "wire" which we assume to have negligible resistance and...
47. ### Lagrangian for a particle in a uniform magnetic field

Any advice on deriving the lagrangian for a particle in a magnetic field? L=\frac{1}{2}mv^{2} + \frac{q}{c}\mathbf{v}\mathbf{.} \mathbf{A} I've been searching through Griffith's, Jackson, and google to no avail. Can we start from the lorentz force and work backwards? Thanks for the help.
48. ### Coil Design for Uniform Magnetic Field?

Dear Forum, I am attempting to make a treatment mattress or pad for PEMF treatment of osteoporosis. I have osteo, and there are commercial units available, but they cost ~\$3K+! I have a capacitor discharge circuit, but need a coil design for the pad. I created a gauss probe with a linear hall...
49. ### Uniform Magnetic Field question

Homework Statement I have a physics final coming up and instead of problems, the final will cover multiple choice conceptual questions. "Several identical charged particles, each with charge Q and mass M, move in a region of uniform magnetic field B. The only force any of the particles...
50. ### Understanding Magnetic Moment in Uniform Magnetic Field

Homework Statement d\hat{S}/dt = γ\hat{S} \times \hat{B} What is the physical interpretation of this equation i.e. what is the behavior of the magnetic moment in an uniform magnetic field?Homework Equations I don't think I need any equation for this, just intuition or vector calculus identity...