Magnetic field Definition and 1000 Threads

Homework Statement Very thin wire bent into the shape of a quarter-circle with the radius R is uniformly charged with electric charge q. Calculate the potential and intensity of the electric field at point A, which lies on a line perpendicular to the plane of the semicircle and is passing...

Consider a 5 meter by 5 meter and 1cm thick superconducting plate, now place a very strong neodymium magnet against the underside of the plate.The plate is big enough so that the magnetic field does not go around the plate. Does a magnetic field penetrate the plate or is it blocked completely...

Question- Two proton beams going in the same direction repel each other whereas two wires carrying current in the same direction attract each other. Why does this happen? Attempt at the solution- Two proton beams should be equal to two currents in the same direction then why are we getting two...

Hello! I'm wondering if there's a general dependency/connection/correlation/function for changes in distance between an electromagnet (coil with iron core) and a magnet (Samarium Cobalt). Here's a picture to explain what I mean: If I move the coil closer to the magnet (smaller x) the force...

Homework Statement A particle of specific charge q/m is projected from the origin of coordinates with initial velocity ##v_1\hat{i}+v_2\hat{j}## in space having uniform electric field and magnetic field as ##-E\hat{j}## and ##-B\hat{j}## respectively. The particle will definitely return to the...

Homework Statement A positron moves in a circular path of radius R due to a uniform magnetic field of strength B applied perpendicular to the plane of the circle. If B is varied, which of the following best represents a graph of the kinetic energy of the positron as a function of B so that the...

I am trying estimate the approximate value in gauss of the magnetic field of a magnet I have based on its pull force, and I am wondering if anyone can comment on the validity of my method. I have tested the pull force of my magnet by weighing the heaviest object it can hold. I have also found...

Homework Statement A uniform magnetic field is perpendicular to the plane of a circular loop of diameter 10 cm formed from wire of diameter 2.5 mm and resistivity 8.5×10-8 Ω·m. At what rate must the magnitude of the magnetic field change to induce a 10 A current in the loop? Homework Equations...

Homework Statement Homework Equations B = μi / 4πR is the equation for a semi-infinite straight wire The Attempt at a Solution I know that for each situation in a,b, and c I would use the equation I listed above, but I am not sure what I would plug in for R for each situation.

How come the magnetic field outside a solenoid is practically zero? I've read reasons along the lines of: -The magnetic field cancels out on the outside. Of course the net force cancels out, but what if you have an object placed on just one spot? The force on that object clearly is not 0...

When deriving the magnetic field strength due to a circular loop at some distance away from it's center (using Biot-Savart's law), why is the angle between ds and r 90 degrees? This is a youtube video with the derivation, see 5:55

Homework Statement Homework Equations EMF induced in a moving wire =Bvl The Attempt at a Solution When right wire is given a velocity v , an initial emf Bvl is induced in right wire due to which current starts flowing in the loop . Initial current i = Bvl/(2R) The left wire experiences a...

Hi everyone, I am trying to calculate the equation of motion of a charged particle in the field of a monopole. The magnetic field of a monopole of strength g is given by: \textbf{B} = g \frac{\textbf{r}}{r^3} And the Lagrangian by: \mathcal{L} = \frac{m\dot{\textbf{r}}^2}{2} +...

Homework Statement **Question** Is the magnetic field directed into the page or out of the page?Homework Equations Right Hand Rule The Attempt at a Solution My index finger is pointing downwards, and since the magnetic force is towards the right and this is an electron (negative) my thumb...

Homework Statement There is a simple set up with a cylindrical solenoid that is connected to a battery. Suppose the solenoid has a total resistance of 0.2 ohms. If the battery were attached to a regular resistor of R=0.2 ohms instead of a solenoid, the current in the circuit would...

I am confused about how the magnetic field of a solenoid is calculated in this image. Why is only the current going into the page included in calculating the magnetic field? Shouldn't the field be twice the amount calculated because there is a magnetic field generated by the part of the turns...

I am trying to understand magnetism and its relation to electricity: Suppose there are two electrons traveling side by side in deep space at 1 cm distance at .99 c In this article http://academic.mu.edu/phys/matthysd/web004/l0220.htm it is said that the ratio $F_B/F_E$ is $v^2/c^2$ for v <<...

An electron beam can be curved into a loop using a magnetic field with flux lines at right angles to the electron beam. These electrons have a high kinetic energy leaving the electron gun. My question is how would a magnetic field effect motionless charged particles for example a cloud of...

If yes, could you please give me a reference documentation? I am an astrophysical amateur. We have published a paper on the frozen-in field lines concept (http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0136936), and are trying to explain the origin of the magnetic field of the...

I have read about Japan's solar power plant in space. Would it not be easier to build a plant similar to the huge circular spinning space stations you see in movies that create their own gravity/downward force? Once something that large is spinning in space could you not use the motion to...

Homework Statement Calculate the magnitude of the magnetic field at a point 100cm from a long, thin conductor carrying a current of 1A. Homework Equations B = ui/2pi(a) The Attempt at a Solution My question is why is this modeled after a problem with an infinite wire? When I first read it I...

Homework Statement Hi! How does a charged particle spiral around a magnetic field lines? Is it because the overal magnetic field interracts with the individual magnetic field of the particle? For example if a piece of metal is put inside magnetic field, the electrons will interract with the...

Homework Statement A particle (mass = 2.0 mg, charge = -6.0 μC) moves in the positive direction along the x-axis with a velocity of 3.0 km/s. It enters a magnetic field of (2i + 3j + 4k) mT. What is the acceleration of the particle in component form? Homework Equations F = q(vXB) F = ma The...

Homework Statement A uniform magnetic field is perpendicular to the plane of a circular loop of diameter 18 cm formed from wire of diameter5.0 mm and resistivity 1.69 ✕ 10−8 Ω · m. At what rate must the magnitude of change to induce a 10 A current in the loop Homework Equations Φ = ∫ B ⋅ dA...

Hi, I would like to know how to get the potential difference due to a constant local magnetic field acting on a wire moving at a constant speed perpendicular to the field. What is the link between F = q v ∧ B and the actual difference of potential in the circuit ? How to determine the induced...

Homework Statement A collection of charged particles move through a magnetic field at an angle to the field lines. Calculate the velocity of the particle if it is an electron moving at 30 degrees to the magnetic field of strength 3.4mT, causing it to experience a force of 4.7x106-18N Homework...

A square loop of wire in the x-y plane, centred on the origin, is made up of four straight segments, each of length 2d=10cm. A current I =10A flows in the wire in the direction shown. Find the magnetic field at z=d on the z-axis. (See "Diagram" for the diagram of the problem) Here is the...

Homework Statement A magnetic lens is made by placing four long, thin current carrying conducting sheets of width ##2a## on the sides of a square, as shown in the figure. The currents in the conducting sheets are distributed uniformly over the sheets, and are directed either into or out of the...

Homework Statement [/B] Homework Equations R = ρ (l/A) I = ε/R s = rθ Magnetic flux = Integral(B ⋅ dA) The Attempt at a Solution [/B] I managed to solve parts (a) and (b) independently. Here is my work for those two parts: My real issue is with part (c) which uses the answers from (a)...

Homework Statement A current 2A flows in a wire. Value of horizontal component of Earth magnetic field in the region is 2x10^-5T. Small compass placed 5cm due north of the wire. Calculate the angle through which the needle deflects due to the current flowing in the wire. Assume u0= 4pi x 10^-7...

According to the article: http://physicsworld.com/cws/article/news/2016/apr/07/birds-measure-magnetic-fields-using-long-lived-quantum-coherence : Is it possible simply to explain mechanism, how two coherent spins of electrons measure direction of magnetic field. I think that this explanation...

A conductor with a large high frequency AC current causes a "Skin Effect" meaning that most of the current flows at the surface of the conductor. What does the skin effect look like if you have a conductor with one side flattened? And what does the resulting magnetic field look like? See...

I'm not sure how magnetic field strenghts and dipoles work. I know that the strenght decreases by 1/r^3, but - isn't magnetic field strenght a constant inherent to the magnet? - if it is not constant, what is? - how is all this related to magnetic damping force?

I should like to ask about the magnetic field of a wire carrying an alternating current (the dimensions of the experiment are too small for radiation to be significant). If I measure the phase of the magnetic field a distance from the surface of the wire, is it still in phase with the current? I...

My last lecture that I have had, was in inductors. My professor said that they resist changes in current, because they store energy inside the inductor as a magnetic field. I know that as soon as you shut off the energy between the inductor, it starts to dissipate, slowly, until it is completely...

Homework Statement A wire is moved with constant velocity such that the motion is perpendicular to the length of the wire in a region containing magnetic field perpendicular to the plane of motion. The wire has a resistance R. Will thermel energy be generated in the wire? Homework Equations...

[Mentor's note: Thread moved from technical sections so no template shown] So the calculations all make sense. But for example to find the direction of B2= 1.33 X 10-5T I believe you should position your right hand like this: Because your thumb should point in the direction of the current...

Homework Statement A doubly charged helium atom (mass = 6.68 x 10-27 kg) is accelerated through a potential difference of 4.00x 103 V. What will be the radius of curvature of the path of the atom if it is in a uniform 0.460 T magnetic field? Note: I hope this question is meant in advanced...

So the main reason I'm posting about this problem is that one of the teaching assistants helped me with this problem, but a buddy of mine got something different on part A and part B (Assess). So I wanted to post up here and see what you guys say. 1. Homework Statement The loop in the...

Let's say we have a north south bar magnet and we place it in a uniform magnetic field such that the magnetic moment is perpendicular to the magnetic field. What happens to the orientation of the magnet? In my view, the magnet receives a torque pointing out of/in to the page that causes the...

Homework Statement So, I got the problem from a friend who told me he copied it down in haste, so it's possible that my confusion stems from a missing variable, but I just want to be certain as my exam is in a few days. So the problem states that there's a +2 helium atom that was accelerated by...

Homework Statement A proton moves through a uniform magnetic field given by = (10−25.3(j-hat) + 30(k-hat))mT. At time t1, the proton has a velocity given by = vx + vy(j-hat)+ (2.0 km/s)(k-hat) and the magnetic force on the proton is B = (4.46 ✕ 10−17 N) + (1.76 ✕ 10−17 N)(j-hat). At this...

Homework Statement The figure shows a cylinder of mass 3.5kg, radius 4.4cm and length 10.2cm with 105turns of wire wrapped around it lengthwise, so that the plane of the wire loop contains the axis of the cylinder. What is the least current which while flowing through the loop will prevent the...

Homework Statement Prove that a current density J(r, t) such that ∇ × J = 0 implies the magnetic field B = 0.Homework Equations Maxwell's equations, vector calculus The Attempt at a Solution I've played around with Maxwell's equations and with the properties of vector calculus but I can't...

Homework Statement Homework Equations ##\oint_{C} Bd\ell = \mu I_{enc}, B_{normal}## continuous across boundary, ##H_{parallel}## continuous across boundary The Attempt at a Solution $$\oint_{C} Bd\ell = \mu I_{enc} \rightarrow B = \frac{\mu NI}{2\pi r}$$ Any help much appreciated. How...

Does anyone know a good program, even a demo for modelling how magnetic fields influence each other? I'd like to run thru some exercises with actual numbers on wjhat kind of field patterns can be made by arranging magnets of same or different strength in different configurations. I should...

Homework Statement The boundary shown is that of a uniform magnetic field directed in the positive z direction. An electron enters the magnetic field with a velocity pointing along the x-axis and exits 0.63 μs later at point A. What is the magnitude of the magnetic field? Homework Equations...

Homework Statement In a wire passes the current I=21A. A part of the wire is bent to form three consecutive sides of a square with sides 40 cm. Find the induction of the magnetic field in the point O which is the center of the square. Homework Equations B=I*μ0*/2*pi*d The Attempt at a Solution...

Homework Statement Find the force that the magnetic field with B=10^-2 T applies on the wire with length 20 cm when it forms with the force the angle 30 grades when in it passes the intensity 5A. Homework Equations F=B*I(intensity)*l(length)*sin alpha The Attempt at a Solution...

Homework Statement See attached photo. It has question and answers. Homework Equations Maybe integral of B.dL=Mo i ? I'm not sure The Attempt at a Solution I tried using the above equation and solved for i but it gives i with respect to time and the answer is 10A. I'm not sure how to get an...