Magnetic force Definition and 416 Threads

In physics (specifically in electromagnetism) the Lorentz force (or electromagnetic force) is the combination of electric and magnetic force on a point charge due to electromagnetic fields. A particle of charge q moving with a velocity v in an electric field E and a magnetic field B experiences a force of





F

=
q


E

+
q


v

×

B



{\displaystyle \mathbf {F} =q\,\mathbf {E} +q\,\mathbf {v} \times \mathbf {B} }
(in SI units). It says that the electromagnetic force on a charge q is a combination of a force in the direction of the electric field E proportional to the magnitude of the field and the quantity of charge, and a force at right angles to the magnetic field B and the velocity v of the charge, proportional to the magnitude of the field, the charge, and the velocity. Variations on this basic formula describe the magnetic force on a current-carrying wire (sometimes called Laplace force), the electromotive force in a wire loop moving through a magnetic field (an aspect of Faraday's law of induction), and the force on a moving charged particle.
Historians suggest that the law is implicit in a paper by James Clerk Maxwell, published in 1865. Hendrik Lorentz arrived at a complete derivation in 1895, identifying the contribution of the electric force a few years after Oliver Heaviside correctly identified the contribution of the magnetic force.

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  1. E

    Direction of Magnetic Force on a Wire Moving Down a Slope with Current I?

    Homework Statement A wire with a current of I (flowing into the screen) moves down on a slope. What is the direction of the magnetic force acting on it? Homework EquationsThe Attempt at a Solution I have no Idea why the answer isn't horizontal, but rather opposing its velocity direction.
  2. H

    Find induced current, magnetic force, work in inclined plane

    Homework Statement [IMG]http://[url=https://ibb.co/b3Emfo]https://preview.ibb.co/gLaEY8/20180527_055248.jpg[ A conducting bar slides down without friction on a pair of conducting rails separated by distance d. Connected to resistor R and there magnetic field B directed upward, perpendicular to...
  3. P

    Current Carrying Wires: How Ampere's Law Affects Safety

    Why don't wires in any circuit touch each other and get short circuited? If two current carrying wires carry charges in same direction then from ampere's law,can't they touch each other due to attractive forces?
  4. M

    Determining the direction of magnetic force

    Homework Statement Referring to (b) in the picture above: What is the direction of the magnetic force on the electron? Homework Equations I use the right-hand rule where by putting your index finger in the direction of the magnetic field and thumb in the direction of the velocity, the middle...
  5. Ignitia

    Magnetic Force with Parallel currents

    Homework Statement A circuit with current I has two long parallel wire sections that carry current in opposite directions. Find magneticfieldatapointPnearthesewiresthatisadistance a from one wire and b from the other wire as shown in the figure. Homework Equations B=μo*I / 2πR The Attempt...
  6. C

    Determining the magnetic force on an electron

    Homework Statement A magnetic field of 0.0200 T [up] is created in a region.a) Find the initial magnetic force on an electron initially moving at 5.00 x106 m/s [N] in the field.b) What is the radius of the circular path? Make a sketch showing the path of the electron. Homework Equations...
  7. E

    What happens to the angle between two wires when one current is doubled?

    Homework Statement We have two very long wires, each with the same mass of 20 grams per meter. They are hung from the ceiling with two identical wires. When they both had the same current flowing to the opposite directions, they created the same angle. We double the current in one of them, is...
  8. E

    The work of the magnetic force

    Homework Statement We put 2 very long parallel wires on a table, in both of them the current flows at the same direction. As a result, they get closer to each other. Does this create a conflict with the fact that magnetic force does not do work? What is the energy source for the work done on...
  9. Biker

    Magnetic force on a current carrying wire

    I was wondering what would happen if you have a current carrying wire that makes an angle with the magnetic field and how to describe its motion. Prepare yourself for the bad drawing. I will first show how the method I used works for a simpler case where Magnetic field and current are...
  10. A

    Why is the magnetic force directed downward in this scenario?

    Good day All! while trying to solve this question I use the right hand rule and according to it the Force should be directed outward (pointing toward me) but here is the answer that puzzeld me I really don't get why it is down , and would feel very grateful if someone can explain me the...
  11. T

    Whether the voltage is actually a magnetic force?

    My question is whether voltage is actually a magnetic force that pushes electrons through the electrical circuit. My question arises from the fact that conductor passes through the magnetic field and if the circuit is closed we have the electron movement as some force pushes the electrons it...
  12. Marc Samarra

    Need references for magnetic force vs distance/angle topic

    Hi, i'm finishing my final degree project, it's about a new type of pallet conveyor dragged by magnets. I know for a fact that magentic force is inversely proportional to the distance squared, and I've designed and built my prototype with that in mind. Now I'm writing my final report and i need...
  13. R

    Magnetic Force Applied to An Object @ d (0,n) (Rail gun on Mars)

    So long story short, I'm trying to write a scientifically accurate short story/animation thing and it revolves around a mass driver: it's a giant and deep hole on Mars with a magnet on the bottom or sides or something and fires packets of objects to Earth at breathtaking speeds (4.66 million...
  14. D

    Magnetic Force -- Confused about the direction of the force

    Homework Statement Homework EquationsThe Attempt at a Solution Hi! I got the magnitude using F=qvB using information from the top of the qs. But the direction is confusing me. I used the Fleming's left hand rule but it sort of isn't giving me the right answer
  15. D

    Magnetic Force direction on a charged particle moving parallel to a wire

    Homework Statement Homework Equations The right hand curl rule gave me the counterclockwise direction for the magnetic field but I am confused about how is it going to work for the particle. Thanks The Attempt at a Solution
  16. D

    Why Does Fleming's Right Hand Rule Give an Upward Force on the Wire?

    Homework Statement Hi! A long, straight, current-carrying wire is placed between a pair of magnets as shown. What is the direction of the force on the wire? Homework Equations Fleming's hand rules The Attempt at a Solution I used the Flemings right hand rule but that gives me that the force...
  17. P

    Motion of a particle in a magnetic field and viscous medium

    Homework Statement In a homogeneous, non-magnetic, highly insulating and viscous medium, a moving particle experiences a viscous drag given by the law f→=−bv→. Here b is a positive constant. A particle having charge q is projected with an unknown velocity from a point in the medium. It almost...
  18. B

    What is the relationship between a force field and a potential field?

    Homework Statement [/B] I have been given an equation for the magnetic potential of a buried magnetic object which is as follows Pm=α/x2 Where α is some constant and x is the distance from the magnetic body. I need to derive an expression for the magnetic field strength at some distance x...
  19. W

    Methods in Calculating with Vector Components

    <Moderator's note: Moved from a technical forum and therefore no template.> Homework Statement A proton (q = 1.60 x 10-19) is in a uniform, 0.500 T magnetic field. This proton has velocity components vx = 1.50 x 105, vy = 0, and vz = 2.00 x 105 m/s. Find the force on the proton at t=0. 2...
  20. X

    Magnetic Force between two solenoids

    Consider two thin and long, single layered identical solenoids with same DC in them, positioned coaxially. I'm trying to calculate the magnetic force on each solenoid, when there are identical magnetic cores inside them. As seen in below, I have the general approximation to the force between...
  21. C

    Calculating Magnetic Force for Homework Assignments

    Homework Statement Homework EquationsThe Attempt at a Solution Is it A?
  22. J6204

    What is the correct magnetic force on the rectangular loop in this figure?

    Homework Statement A rectangular loop of wire, L = 28.8 cm and W = 15.2 cm, carries a I1 = 2.02 A current and lies in a plane (d = 11.0 cm), which also contains a very long straight wire carrying a I2 = 12.7 A current as shown in the figure below. Homework Equations F=uo*i1*i2*l/perpindicular...
  23. Hardik Batra

    Magnetic force relation with v and r?

    (1) Magnetic force acting on charge moving in magnetic field is given by, F = qvBsinθ...F ∝ v This means that if moving charge particle has more velocity then more magnetic force will act on it. Due to more magnetic force the direction of velocity changes rapidly and it will move on the...
  24. G

    Can someone help me find an equation for magnetic force?

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  25. H

    Electrons move, causing magnetic force, find v?

    Homework Statement Homework Equations f = q.v.B.sin tetha I = q/t = v/R The Attempt at a Solution (1) q =a.b.n.v.t is it right? (2) I = q/t = abnvt/t = abnv is it right? (3)F = q.v.B is it right? (4) ? (5) ? is it right?
  26. A

    Why is this loop pushed downwards by the magnetic field?

    Homework Statement 2. Homework Equations FB = ∫I ds×B The Attempt at a Solution My first guess was that it would not move at all. I understand that there is an induced magnetic field in the opposite direction but wouldn't the induced field produce a current counterclockwise, which, since...
  27. R

    Magnetic force on triangular loop of wire

    Homework Statement Find the force on the triangular loop in the figure: I am trying to do this in cylindrical polar coordinates, because it builds character. Homework Equations $$\vec{B}(\vec{r}) = \frac{\mu _0}{4\pi} \int \frac{I(d\vec{l} \times \hat{\alpha})}{|\vec{\alpha}|^2}$$ Where alpha...
  28. S

    Magnetic force on current carrying wire

    Homework Statement A wire along the z-axis carries a current of 6.8 A in the +z direction. Find the magnitude and direction of the force exerted on a 6.1-cm long length of the wire by a uniform magnetic field with magnitude 0.36 T in the -x direction. Homework Equations F=I(LxB) The Attempt...
  29. F

    Difference in formulas of magnetic force and magnetic flux

    The magnetic force is defined as ## \rm F_e = Bqvsin\theta## and the magentic flux is defined as## \rm \phi = BAcos\theta## My question is since we are multiplying the two vectors, why is ##sin\theta## used in one equation and ##cos\theta## in second given that ##\theta## is the angle between...
  30. Asmaa Mohammad

    When will two current-carrying wires touch each other

    Homework Statement Two wires are free to move, the current in each one is 10 A, the mass of each one is 2.5 g, they are separated by a distance of 20 cm, and the length of each one is 5 cm. Determine (i) where and (ii) when will the two wire touch each other if they were standing parallel to...
  31. S

    What is magnetic force generated by planar spiral coil?

    Hello everybody, I have a planar spiral coil with wire. I want to move a magnet in vertical direction with the magnetic force generated by coil. I want to know how much impulsion to magnet will be occurred on vertical direction. I have been searching for the answer but I am a little bit...
  32. J

    Do photons carry magnetic force?

    I understand that in the standard model, photons are the carriers of the EM force. Does that apply to a normal bar magnet? I.e., when you sprinkle iron filings near a bar magnet and the filings align along the field lines, does that mean that photons are being exchanged between the magnet and...
  33. Passionate Eng

    How does a magnetic force affect the movement of charges and magnets?

    If magnetic force does not exert work on moving charges, how could a current loop immersed in a magnetic field rotate and how could a magnet attract or repel another one?
  34. N

    Magnetic flux and how to manipulate it discussion anyone?

    Good day all, I am looking to discuss how to manipulate the magnetic flux of a coil. I unfortunately lack the math skills to calculate what I actually need to build for my project. I have been coop up in my garage trying to physically solve the problem but I am running out of time and money for...
  35. Eri ep

    I Differentiating Biot-Savart Law

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  36. joeyc

    Force per unit length acting on four parallel wires

    Homework Statement An arrangement of four wires, in cross section, with θ=30° and u=5cm. Wire 2 and wire 4 carry the same magnitude of current (I2=I4=10mA) directed out of the page. Wire 3 carries current I3=25mA directed into the page. If the resultant force per unit length on wire 1 is zero...
  37. RoboNerd

    Torque on wheel in magnetic field

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  38. G

    I Deriving Magnetic Force w/ Approximated Gamma-Factor at UVA

    Hi. On the webpage of a lecture at the University of Virginia, I found this derivation of the magnetic force using Lorentz contraction and electrostatic force. They approximate the gamma factor to the order of ##v^2## and get the correct result. How is it possible to get to the same result...
  39. Schaus

    Calculating Electron Velocity in Crossed E and B Fields

    Homework Statement What velocity does an electron need to have in order to travel straight through the crossed E and B fields, given that E = 1.0 x 105 N/C and B = 0.40 T? Answer: 2.5 x 105 m/s Homework Equations E=F/Q F=BIl F=QvB[/B]The Attempt at a Solution 1.0 x 105N/C / 1.6 x 10-19 = 6.25...
  40. U

    Help with magnetic force from fault current on overhead wire

    I'm trying to resolve an issue I'm experiencing with some overhead power distribution lines, was wondering if anyone can help me out. Here is the scenario: three phase, 4 wire, wye connected 13.4kV power distribution system. 556.5kcmil bare ACRS wire is mounted on a crossarm 24" apart over a...
  41. S

    Calculating magnetic force on semicircle conductor

    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...
  42. mohau tshekoeng

    Is it possible to calculate the magnetic force between magnets?

    Hello I am a a grade 11 learner and I am trying by all means to calculate force between magnets. I know that the strength of a magnetic field is determined by the size of the magnet.
  43. AvroArrow

    Magnetic Force that Makes a Solenoid Valve Work

    Hi guys, I am having quite the struggle finding a good resource to explain the difference between the magnetic force associated with moving charged particles (Lorentz Force) and just the regular force exerted by a magnetic field on a magnet or ferromagnetic material. I am trying to apply this...
  44. M

    Find Magnetic Force: Electron & Proton

    Homework Statement An electron that has a velocity with x component 2.1 × 106 m/s and y component 3.1 × 106 m/s moves through a uniform magnetic field with x component 0.035 T and y component -0.16 T. (a) Find the magnitude of the magnetic force on the electron. (b) Repeat your calculation for...
  45. P

    I Question about the formal definition of conservative force

    So, I was reading the mathematical description of a conservative force o wikipedia : https://en.m.wikipedia.org/wiki/Conservative_force and at the line "Many forces (particularly those that depend on velocity) are not force fields. In these cases, the above three conditions are not...
  46. G

    I Discrepancy in Co-Moving Charges Magnetic Force?

    Consider two identical charges separated by some distance. Both are moving together with the same velocity, and the velocity vectors are perpendicular to a straight line drawn between the charges. Each charge has charge q, speed v and they are separated by a distance of r. In the rest frame of...
  47. C

    Explaining Magnetic Force on Iron Without Moving Charge

    Hi, I am a high school physics student and the only ways we learned to calculate the magnitude of a magnetic force involved a moving charge or current in a wire. As a result I have wondered how a bar magnetic magnet may exert a force on a piece of iron, since there is no clear movement of charge...
  48. terryds

    What is the magnitude and direction of the current in conductor RS?

    Homework Statement As shown in figure above, a conductor RS with 2 m length which is powered with currents is put in a 0.5 T magnetic field. If the force generated by the conductor is 1 N into-the-screen, then the magnitude and direction of the current in conductor is ... A. 1 A from R to...
  49. N

    Determining Direction of Magnetic Force on a Moving Bar Magnet Near a Wire Loop

    Homework Statement A bar magnetic is moved along the axis of a circular wire loop. In the figure below, (A) and (C) show the bar magnet moving toward the wire loop, while (B) and (D) show the bar magnet moving away from the wire loop. Image: https://gyazo.com/2944a79393e7955214b281da58e7b0b8...
  50. M

    Magnetic Force on Electric Currents

    1. A current in a wire which has a length of 2.00m in a magnetic Field of 0.030 Teslas, feels a magnetic force of 0.810 Newtons. What is the current in the wire?2. F=IlB, Find I3. F= 0.810, l= 2.00m, B= 0.030 T, I=? (A) I= l x B I= 2.00m x 0.030 T I= 0.074 A F...
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