Current loop Definition and 93 Threads

  1. F

    Force on a Rectangular Current Loop [Magnetism]

    Homework Statement A force acts on a rectangular loop of wire, pulling it out of a magnetic field. Calculate the force required to pull the loop to the right at a constant speed of 4.42 m/s. B = 0.44 T l = 0.350 m v = 4.42 m/s R = 0.356 ohms Homework Equations Fmagnetic=I*l*B...
  2. G

    Current Density of Circular Current Loop (Jackson)

    Hi, I was reading through Jackson's Electrodynamics trying to reason through example 5.5 for the vector potential of a circular current loop of radius a centered at the origin. I pretty much understand everything except when he defines the current density as J_{\phi} = I\sin \theta'...
  3. H

    Magnetic field due to an uneven current loop

    Homework Statement "A closed circuit consists of two semicircles of radii 40cm and 20cm that are connected by straight segments. A current of 3.0 A exists in this circuit and has a clockwise direction. Find the magnetic field at point P (center of the figures).Homework Equations B = (mu *...
  4. Z

    Calculating EMF in a Current Loop: 1000 Revolutions/Min with B = 0.45 T"

    Hi all, I have a certain problem I'm getting stuck on hopefully someone here can help Homework Statement A rectangular coil is 75 mm wide in the y-axis, 100mm long in the x-axis. What is the speed of the rotation if an rms voltage of 0,25 V is developed in the uniform field of B =...
  5. J

    Off-axis magnetic field due to a current loop in cartesian coordinates

    Hi there, a few days ago I derived the probably well-know expression for the magnetic field of a current loop including elliptic integrals of the first and second kind (it can be seen here http://plasmalab.pbworks.com/f/bfield.pdf" ). As I'd like to rotate and shift the position of the...
  6. R

    Proving DC Current Loop Does Not Radiate w/ Lienard-Wiechert Potential

    Homework Statement Hi guys, on chapter 14 in Jackson's classical electrodynamics, problems 24 asks to prove that a dc current loop does not radiate, starting from Lienard-Wiechert potentials for the individual charges q. The distance between them is \Delta. We should move to the continuous...
  7. N

    Will a current loop precess or align with a magnetic field?

    Hello, When I have a current loop (macroscopical, but I don't know if that matters) in an external magnetic field such that the loop's magnetic moment vector is not aligned with the magnetic field, I know it'll create a torque on the loop to align it with the B-field. I was wondering: does...
  8. K

    Cartesian equation for the Magnetic field resulting from a single current loop?

    Hello I am carrying out some analysis on the magnetic field generated over a 3D region by a single current loop. The present form of the equations is in cylindrical coordinates and is as follows \vec{B}={Brc,0,Bz} There is no angular component in this present from. Note: The following website...
  9. N

    Biot-Savart current loop equation confusion?

    Hello, I am having a bit of a problem with this classic example. I know about the symmetry but I would like to push through the math anyway. The field point is at distance Z from loop on Z axis. Using cylindrical coordinates I am at: dH = I*(rho)d(phi)*a(phi) X (z*az - rho*a(rho)) /...
  10. K

    What is the current in the current loop?

    Homework Statement It is important to be completely isolated from any magnetic field, including the Earth's field. A 1.00m diameter current loop with 200 turns of wire is set up so that the field at the center is exactly equal to the Earth's field in magnitude but opposite in direction. What...
  11. B

    CURRENT LOOP Q. i HAVE ATTEMPTED, JUST NEED CORRECTION OR REJECTIONTHANKS

    [b]1. Homework Statement A 4-20mA current loop is being used to transfer temperature values in the range + 10ºC to +60ºC. (i) What temperature is represented by a current of 7mA? (A) What current would you expect when the temperature of the sensor is 32ºC? Homework Equations i HAD AN...
  12. S

    Determining Forces on a Current Loop in a Magnetic Field

    Homework Statement A current loop that lines in the horizontal plane consists of a straight line segment 2R and semicircular segment with a radius R. A current I flows through the loop (assume counterclockwise direction), and a uniform magnetic field B points outward of the page everywhere...
  13. C

    Magnetic Field of rectangular current loop

    Homework Statement Find the magnetic field of a rectangular current loop lying symmetrically on the xy-plane. Find the magnetic field at (0,0,z) Homework Equations Biot-Savart law or derived formula (Mu/4*Pi) * sin(theta2)-sin(theta1)/s The Attempt at a Solution I am NOT good...
  14. B

    Question about charged disk and current loop similarity

    I have a question regarding the similarity between the Biot-Savart law and the equation that gives the magnetic field inside a current loop, and the similar version of Coloumb's law that gives the electric field due to a charged ring. In the equation for a charged ring at...
  15. T

    Torque on a current loop about a hinge line

    Homework Statement A rectangular 20 turn loop that is 12 by 5 cm carries a current of 0.10A. It's hinged at one of the longer 12cm sides. It's mounted with its plane at an angle of 33 degrees to the direction of a magnetic field of 0.50T. What's the torque about the hinge line? Homework...
  16. E

    Magnetic field due to current loop

    Homework Statement Homework Equations \vec B = \frac{\mu i \phi}{4 R} The Attempt at a Solution The field due to the curve R_1 is: \vec B = \frac{\mu i \phi}{4 R} \vec B = \frac{(1.26x10^-6)(.281)(\pi)}{4 (.023)} = -1.21x10^-5 \hat k The field due to the curve R_2 is...
  17. D

    What is the least current to prevent the cylinder from rolling down the incline?

    Homework Statement A wood cylinder of mass m = 0.250 kg and length L = 0.100 m with N =10 turns of wire wrapped around it longitudinally, so that the plane of the wire coil contains the long axis of the cylinder. The cylinder is released on a plane inclined at an angle theta to the horizontal...
  18. S

    Magnitude of the maximum torque on a current loop.

    Homework Statement A current loop in a motor has an area of 0.62 cm^2. It carries a 207 mA current in a uniform field of 1.43 T. What is the magnitude of the maximum torque on the current loop? A = .0062 m^2 I = .207 A B = 1.43 T Homework Equations F=(IA)Bsin(theta) The Attempt...
  19. M

    Electric field of a current loop

    What is the electric field outside a steady state current loop? Why is this not discussed in textbooks?
  20. C

    Magnetic Field - Torque on a Current Loop

    Homework Statement A circular coil of 720 turns and area 0.6 m^2 is in a uniform magnetic field of 0.63 T. The maximum torque exerted on the coil by the field is 0.0026 N · m. a) Calculate the current in the coil. b) Assume the 720 turns of wire are used to form a single-turn coil with the...
  21. J

    What is the Magnetic Field at the Center of a Current-Carrying Loop Segment?

    Homework Statement A loop carries current I = 2.5 A in the x-y plane as shown in the figure above. The loop is made in the shape of a circular arc of radius R = 4 cm from qo = 60 ° to q = 360 ° . The loop is completed by horizontal and vertical sections as shown. What is BA, the magnitude...
  22. L

    Calculate Flux Density of Current Loop

    Homework Statement Loop like an "O" with current moving to the left Diameter = 8cm Current = 15A FIND THE FLUX DENSITY OF THE CURRENT LOOP IN THE PLACE OF THE LOOP? Homework Equations B(flux density)=F(magnetic flux)/A(area) B=H(magnetic field strength)*Permeability H(magnetic field...
  23. C

    Magnetic field on current loop, involves rotational energy

    Homework Statement A rectangular loop of sides a = 0.3 cm and b = 0.8 cm pivots without friction about a fixed axis (z-axis) that coincides with its left end (see figure). The net current in the loop is I = 3.2 A. A spatially uniform magnetic field with B = 0.005 T points in the +y-direction...
  24. D

    Magnetostatics - field of a current loop

    Homework Statement Find the magnetic field at the center of a square loop, which carries a steady current I. Let R be the distance from center to side.Homework Equations Biot-Savart for a steady line current: B(r) = μI∫ dl X r ---- ----------------------...
  25. I

    Calculating Torque & Angular Acceleration of a Current Loop

    Homework Statement A small current loop of area A = 1.5cm^2 carries current I = 3.6mA. What torque acts on it in a lab where its magnetic moment is perpendicualr to the Earth's magnetic field of 4.2 x 10^-5 (b) Find its angular acceleration if its rotational inertia about a diameter is...
  26. G

    Magnetic field/simple current loop

    given a current loop, centered at the origin, and tilted 90 degrees so that it enters at x=1 and exits at x=-1, carrying a unit amount of current, and completely disregarding the z axis. is the strength of the magnetic field at any point in the xy plane proportional to 1/(distance from...
  27. L

    E-field from Time Varying B-field of Current Loop

    I am trying to calculate the E-field from a varying B-field. The B-field is from a current loop. \vec{B}(\vec{r},t)=\vec{B_{0}}(\vec{r})Sin(\omega t) where \vec{B_{0}}= http://www.netdenizen.com/emagnet/offaxis/iloopoffaxis.htm" Now since B is varying with time there should be an electric...
  28. P

    Torque on a Current Loop in a B Field

    Homework Statement A 119 cm wire carries a current of 1.5 A. The wire is formed into a circular coil and placed in a B-field of intensity 1.9 T. 1) Find the maximum torque that can act on the loop. 2) How many turns must the coil have, so that the torque is maximized? Homework...
  29. H

    Interaction of a Current Loop with a Magnetic Field

    Homework Statement Assume that the current flowing into the loop is 0.500A . If the magnitude of the magnetic field is 0.300 T, what is torque , the net torque about the vertical axis of the current loop due to the interaction of the current with the magnetic field? the loop is initially...
  30. S

    Magnetic Field due to a current loop

    [SOLVED] Magnetic Field due to a current loop Homework Statement A single loop of wire of radius 3 cm carries a current of 2.6 A. What is the magnitude of B on the axis of the loop at 2 cm? Homework Equations B=\mu/(4\pi) * 2\pi(R^2)*I/(z^2+R^2)^(3/2) The Attempt at a...
  31. E

    Current loop + perpendicular current : magnetic field?

    Homework Statement Hi, it's my first post and I'm not sure whether it's the right category to post anyway. Please help me though :) I have to "construct" theoretically a superposition of magnetic fields for the introduction of my tokamak-related diploma thesis. First task was to find the...
  32. F

    How Does Electromagnetic Theory Explain Forces in a Moving Rod?

    This question is a little bit more difficult. I'm not too sure if I'm in the right place to be posting this type of question- but here it is: Type: Theory Question regarding electromagnetism My professor is an extremely difficult person to understand. His notes are all over the place and...
  33. M

    How Is Induced EMF Calculated in a Current Loop with Increasing Current?

    Homework Statement If the current is increasing at a rate of 0.1 A/sec what would the induced emf in a loop of 0.5 m be? Homework Equations I = \frac{|emf|}{R} emf = - \frac{d}{dt} B A cos(\theta) I'm obviously missing an equation or something. Some guidance would be much...
  34. R

    Magnetic field generated by a circular current loop

    Hello everybody! I have some trouble determinating the magnetic field generated by a circular loop of current. I'd use it as an approximation for the poloidal field in a Tokamak (field generated by the current in the plasma). I tried using Biot-Savard's Law but I'm getting stuck... I hope to...
  35. S

    Square Loop Current: Vector Potential Zero w/ 2 Sides

    how could a current in a square loop has a vector potential be zero due to 2 sides only.
  36. J

    Magnitude of induced emf in current loop

    Homework Statement The 2-cm (radius) current loop shown in the figure is changing from θ1 = 11 degrees to θ2 = 66 degrees in a magnetic field 2 T in 0.5 seconds. What is the magnitude of the induced emf to the nearest hundredth of a millivolt. The wire in Problem 2 has a thickness of 1.04...
  37. D

    MATLAB Off-axis Magnetic Field of Current loop (MATLAB?)

    I have checked the forums for similar problems and have only seen that one would use 'MATLAB' to perform this integration. All I want to do is find the 3 components of the magnetic field at a point (x, y, z) off of the axis of a current loop (given current, radius and that the loop lies on...
  38. O

    Magnetic field from rectangular current loop

    Another doozie for me. I have been trying this one for 3 days now. I will give my first born for help to this one :rolleyes: --------------- Calculate the magnitude and direction of the magnetic field produced at point P in Fig. 28.52 by the current I in the rectangular loop. (Point P is at...
  39. O

    Magnitude of torque on a current loop

    I've given this one a good effort and I cannot seem to solve it, been trying for a couple days on my own now...Anyone able to lend a hand? I was using t=uxB(u cross B) to find the torque and then take the negative of it to find the torque that is to hold it? vector u = I(vector A), and for...
  40. V

    Understanding Torque on a Current Loop in a Uniform Magnetic Field

    Hey. I've read in my text that the netforce acting on a current loop in a uniform magnetic field is zero. But, in the next section, it mentions how torque is exterted on a loop placed in a uniform magnetic field. How can this be if the netforce must be zero? (I think I am making a really simple...
  41. S

    Force and Torque of a Clockwise Current Loop in Magnetic Field

    A rectangularl oop carring a clockwise current i is placed in a constant magnetic field B = By. The four corners of the loop are at (x=0, y = +/- a/2, z=+/-b/2 where a and b are positve onstants find the force and torque, magnitude and direction on each of the four straight lin segments of the...
  42. N

    Derivation for Magnetic Dipole of Current Loop

    Hi All, Please show me the derivation of the vector potentiol A for the magnetic dipole. from equation 8.21 to 8.21a This page is taken from Sadikus book. ** i tried all day and couldn't manage to obtain it. i need the derivation step by step ** thanks newbie...
  43. F

    Net Magnetic Force on Rect. Current Loop

    A rectangular current loop (L=0.40 m and W=0.19 m) is located near a long, straight wire (d=0.10) that carries a current of 10 A (see the drawing). The current in the loop is 20 A. The Determine the magnitude of the net magnetic force that acts on the loop. i was chugging my B from the wire...
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