What is Induced current: Definition and 201 Discussions

Electromagnetic or magnetic induction is the production of an electromotive force across an electrical conductor in a changing magnetic field.
Michael Faraday is generally credited with the discovery of induction in 1831, and James Clerk Maxwell mathematically described it as Faraday's law of induction. Lenz's law describes the direction of the induced field. Faraday's law was later generalized to become the Maxwell–Faraday equation, one of the four Maxwell equations in his theory of electromagnetism.
Electromagnetic induction has found many applications, including electrical components such as inductors and transformers, and devices such as electric motors and generators.

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  1. M

    Can Induced Currents Be Used to Increase the Efficiency of Electric Cars?

    I think we could take advantage of the induced current, created inside a loop when it passes through a magnetic field. So placing the coil on an electric car and connecting it with the battery, the car will receive a small electrical charge will pass through a magnetic field (to be created on...
  2. A

    Magnitude and Direction of Induced Current on a wire around a cylindrical volume

    Homework Statement A uniform magnetic field B is confined to a cylindrical volume of radius 0.080m. B is directed into the plane of the paper and is increasing at a constant rate of (delta)B/(delta)t=0.300 T/s. Calculate the magnitude and direction of the current induced in a circular wire...
  3. U

    What is the direction of the induced current in the loop for each situation?

    Homework Statement THe problem is number 3 in the picture. Homework Equations The Attempt at a Solution Lens law changing magnetic flux through the loop not sure which way for each one little confused. Thank you
  4. C

    Induced current due to rotating coil

    I attached a problem from a practice exam. I'm stuck on part b). Part A, I'm assuming the answer is the standard equation for an infinite current sheet. How do I find induced current? I can only think of using Emf = NBA*ωsintωt Where Emf= I/R, but I don't have resistance. Only other equation I...
  5. S

    Answer: Calculating Induced Current in NMR

    Hi, Question: we have a magnetization M_x that varying as M_x(t)=M_x e^{-t}.Threre is a coil on the x axe. The magnetization will induce a current in the coil. How can get value of this current. This situation happen in NMR device. I try to caculate magnetic flux and then voltage (v=-N...
  6. B

    Find the direction of the induced current

    Homework Statement ◎ There are two solenoids with their axes parallel, one with a smaller diameter so that it fits inside the other. If the bigger solenoid has a current flowing in the clockwise direction (looked at from above) and the current is increasing in magnitude, find the direction of...
  7. O

    Induced current in a two-loop circuit

    Homework Statement I am using these variables: L for the square length - so the rectangle on the left is L/2 by L B' = rate at which field increases λ = Resistance/Length I1 = Current on the right (so the top/right/bottom of square) - goes counterclockwise I2 = Current on the left (so the...
  8. G

    Calculating Induced Current in a Solenoid-Loop Circuit

    Homework Statement A cylindrical solenoid 30 cm long with a radius of 8 mm has 400 tightly-wound turns of wire uniformly distributed along its length (see the figure). Around the middle of the solenoid is a two-turn rectangular loop 3 cm by 2 cm made of resistive wire having a...
  9. I

    Magnetic Field Induced Current Problem

    Homework Statement http://tinypic.com/r/rlidg7/5 The picture above shows four different cases of a conducting square loop (in orange), traveling at speed v and passing through a rectangular region. In the left half of the rectangular region, the magnetic field is uniform and directed into...
  10. L

    What is the induced current?

    Problem: A long vertical wire carries a steady 17 A current. A pair of rails are horizontal and are 0.2 m apart. A 7.6 Ω resistor connects points a and b, at the end of the rails. A bar is in contact with the rails, and is moved by an external force with a constant velocity of 0.5 m/s as shown...
  11. T

    Rate of Field Change for Induced Current of Loop

    Homework Statement A single conducting loop of wire has an area of 8.0×10−2 m^2 and a resistance of 110 Ω. Perpendicular to the plane of the loop is a magnetic field of strength 0.37 T. At what rate (in T/s) must this field change if the induced current in the loop is to be 0.33 A...
  12. phosgene

    Determine the direction of induced current in a wire

    Homework Statement A wire carrying a current experiences a force when it is placed in a magnetic field. This phenomenon forms the basis of many devices including the electric motor and the gavlvanometer. The diagram shows a uniform magnetic field B with magnitude 25mT directed towards the...
  13. S

    Average Torque on an Induced Current Loop

    Homework Statement A rectanglar loop of wire encloses an area A, has a resistance R and a self-inductance L. The loop is suspended from the mid point of one of its sides and placed in a horizontal oscillating magnetic field B = B0 sin ωt such that the field makes an angle θ with the normal to...
  14. T

    Determining direction of induced current

    How do you determine that direction of the AC current at a given instant in this model. Does it really matter? The red arrows change direction when the coil is horizontal. Does anyone know why the current changes direction at that point? Why does it switch direction at the horizontal and not the...
  15. W

    Induced current in conductor moving circularly in constant B-field

    Homework Statement A light bulb with resistance R is attached on a metal rod which is rotating around the point O on the figure. The metal rod is in contact with an electrical conductor which is a part of a circle with radius d. The metal rod and the circular electrical conductor is a closed...
  16. I

    Induced current in a loop circuit magnetic field

    Homework Statement Homework Equations I know this is supposed to use Lenz's law, but I don't really understand it V=IR The Attempt at a Solution I calculated the resistance of the circuit to be 6.4e-6 / .0015 = 0.00426666667, but that's as far as i know what to do
  17. C

    Lenz' Law, induced current in a ring falling

    Homework Statement A ring falls through a horseshoe magnet. Before reaching the magnet, is the current induced in the ring clockwise or counterclockwise? What about after the ring has passed through the magnet? The answers are clockwise before the ring passes through, and...
  18. J

    Finding induced current (Lenz's Law)

    Homework Statement Attached below Homework Equations Emf = - \Delta\Phi / \Deltat emf = vBl; motional emf The Attempt at a Solution In the two attached files, there are problems that ask for the direction of the induced current. I understand that the induced current flows in the...
  19. A

    Induced current in expanding metal ring

    Homework Statement A circular metal ring, as shown on the diagram below, is constructed so as to expand or contract freely. In a region with a constant magnetic field Bo oriented perpendicular to it, the ring expands, with its radius growing with time as r=r0(1+\alphat2). As the ring expands...
  20. C

    Magnitude of the induced current in the loop

    Homework Statement A rectangular conducting loop of dimensions l×w and resistance R rests in the plane of a long straight wire as shown. The closest edge of the loop is a distance a from the wire. The current in the wire is in the upward direction and increases at a constant rate from I to...
  21. S

    Direction of Induced Current in a Small Loop Inside a Solenoid

    Homework Statement This is a question from the Princeton Review of AP physics B, 2011 edition. A small circular loop of wire (radius r) is placed on an insulating stand inside a hollow solenoid of radius R. The solenoid has n turns per unit length and carries a counterclockwise current I...
  22. C

    Magnetic Flux Induced current

    Say I have a closed metal rectangular shaped wire in a region with a magnetic field. If the magnetic flux is constant, there is no induced current, no experienced force, and no EMF? If I start the changing the magnetic flux, I suppose by increasing the magnetic field, there will be an...
  23. I

    Bar magnet at constant velocity, what is the direction of the induced current?

    Homework Statement A bar magnet is spun at constant angular speed w around an axis as shown in Figure P31.38. A stationary flat rectangular conducting loop surrounds the magnet, and at t = 0, the magnet is oriented as shown. Make a qualitative graph of the induced current in the loop as a...
  24. F

    Induced Current Direction in a Moving Square Loop

    Homework Statement The square loop in the figure below is made of wires with a total series resistance of 10.0. It is placed in a uniform 0.100 T magnetic field directed perpendicular into the plane of the paper. The loop, which is hinged at each corner, is pulled as shown until the...
  25. J

    Induced Current in a Loop - Changing B Field

    Apologies if this is not in the proper location/format/etc; first post. In a very short (3 min) segment on MythBusters, they unsuccessfully tried to induce a current in a loop in the same plane as a current carrying wire (AC). I originally assumed this didn't work because the B field was not...
  26. R

    Electromagnetic Induction, How to find direction of induced current?

    Homework Statement I have a few homework questions that ask for the direction of induced current for ex a loop of wire. I can't figure out how to find it .
  27. B

    What is the difference between eddy current and induced current?

    what is the difference between eddy current and induced current? and how could eddy current cause energy loss? does the induced current cause also energy loss? what is the difference between back emf and induced emf? all these things are confusing me. thanks in advance
  28. Z

    Induced current due to a Solenoid

    Homework Statement Two metallic rings A and B, identical in shape and size but of different resistivities Pa and Pb are kept of the top of two identical vertical solenoids. When current I is switched on in both the solenoids in an identical manner, the rings A and B jump to heights ha and hb...
  29. N

    Induced current with standing magnetic field

    Hi there, When you have a loop of wire and you move a bar magnet through it, you induce a current in the wire. What if you were in a room where there was a magnetic field (not moving) that was stronger than the magnetic field produced by the magnet? If you moved the magnet through the loop...
  30. E

    Direction of induced current explanation

    Homework Statement (Draw a diagram illustrating the direction of the electric current induced in a conductor as it passes through a magnetic field) Write a short paragraph in which you explain your reasoning for the direction of the current in your diagram refer specifically to the motor...
  31. D

    Induced Current and Magnetic Fields

    Homework Statement Hey everyone, I'm studying for a final and have been having difficulty determining induced magnetic field and current direction. I have a document (link below) with 5 sample problems. I answered them all, and put my reasoning for the answers there in italics. Would...
  32. M

    Magnetic sphere and induced current

    Hey guys, I have a scenario where I can't figure out what would happen. If I have a magnetic sphere traveling down a track made of two conducting wires (each with current flowing through them)... what would happen? I'm not sure how the magnetic field of the wire and the magnetic field of...
  33. Z

    Back EMF and induced current

    Homework Statement Describe with the aid of diagrams how the back emf and induced current vary in a single-coil DC motor over one full rotation of the armature. Give particular attention to the rate of change of flux in the coil and to the direction(s) of the DC and induced current...
  34. R

    Calculating Induced Current in a Coil of Wire

    Homework Statement A flat coil of wire consisting of 20 turns, each with an area of 50 cm2, is positioned perpendicularly to a uniform magnetic field that increases its magnitude at a constant rate from 2.0 T to 6.0 T in 2.0 s. If the coil has a total resistance of 0.40 Ω , what is the...
  35. P

    Induced current problem in COMSOL

    Hi everyone, I'm working on COMSOL's ac-dc module and I'm trying to find the magnetic field which is created by an electrode pair (dipole). The working environment of the pair has nonzero conductivity and relative permittivity. I first found the current density between the electrodes in...
  36. M

    Calculating Induced EMF and Current in a Moving Bar with Magnetic Field B = 1 T

    Homework Statement A bar of 1 m length aligned in y direction moves in +x direction at 10 m/s, in space where B = 1 T pointing in the -z direction. Calculate the motional EMF. If the bar above, is a part of a circuit with a light bulb of 10 ohms resistance, what would be the induced current...
  37. N

    Induced current in a static magnetic field

    I'm a bit confused about magnetism and electromagnetic induction. On the one hand I understand that to induce a current we need a change in magnetic flux. On the other... a charge moving relative to an external magnetic field experiences a force. If the field is uniform then we would...
  38. C

    What is the principle behind measuring power in 3 phase systems using coils?

    Can anyone point me to a good site that explains current induction, specifically when a coil is placed around an energized, current carrying conductor? I would like to understand this principle to understand how power can measured in 3 phase power systems by using coils as a measuring element.
  39. 7

    Magnetism and induced current

    I dabble in miniature milling/machining with my home CNC setup. I'm building a low temperature engine and have a question. The piston will be a neodymium magnet(s) set in graphite. Rather than using mechanical linkages and a crankshaft I want to use magnets to control the length of throw. By...
  40. T

    Why does induced current in loop vary twice with rotation of coil?

    A square loop of wire of side a is rotating with frequency \omega in a magnetic field. I understand that at time t, a magnetic field B=B_{0}sin\omega t passes through the loop. But why does the current induced in the loop vary twice with the frequency of rotation? What is the expression of...
  41. C

    Direction of induced current in metal loop

    Homework Statement A metal loop is attached to an axle with a handle as shown. The north pole of a magnet is placed below the loop and the handle turned so that the loop rotates counterclockwise at a constant angular speed. On the two diagrams below, indicate the direction of the induced...
  42. L

    What Direction Does the Induced Current Flow When a Magnetic Field Decreases?

    A magnetic field B, that is decreasing with time is directed out of the page and passes through a loop of wire in the plane of the page, as in my drawing (ignore that the dots are not evenly spaced, you can only do so much in paint) Which of the following is true of the induced current in the...
  43. D

    Induced Current Density On Disk Due to Changing Magnetic Field

    Homework Statement A very thin conducting disc of radius a and conductivity \sigma lies in the x-y plane with the origin at its center. A spatially uniform induction is present and given by B=B_0 cos\(\omega t \)\hat{z}. Find the induced current density \vec{J} in the disc. Homework...
  44. S

    Induced Current - is there one if inside constant B field?

    Homework Statement A box of wire is moving within a constant B field. Is there an induced current? Homework Equations Slap rule The Attempt at a Solution Since the wire is experiencing constant B field, how would we figure out whether or not there is a current? I know there is a...
  45. S

    Magnitude and direction of induced current with magnetic field

    Homework Statement A conducting rod whose length is 25 cm is placed on a U-shaped metal wire that has a resistance of 8 ohm. The wire and rod are placed in the plane of the paper. A constant magnetic field of strength 0.40 T is applied out of the paper. An applied force moves the rod to the...
  46. R

    Induced current in moving Mercury

    Hello everyone, This question is the third question from the 2001 IPhO: Problem text: http://www.jyu.fi/tdk/kastdk/olympiads/2001/IPhO2001-THEO.pdf Solution text: http://www.jyu.fi/tdk/kastdk/olympiads/2001/IPhO2001-THEO-SLN.pdf I'm having trouble understanding how they came to the conclusion...
  47. V

    What is the induced voltage in the tilted coil frame?

    Homework Statement As shown in this picture: a 18 cm long solenoid with 1500 loops (N = 1500) and radius 2 cm is located at the center of wire frame (coil) that is 5(width) by 8(height) cm. There is a current inside of solenoid that is growing from 0 to 2.5 A in 7.5 seconds that rotates...
  48. C

    Would the direction of the induced current change if the current falls?

    when a current in a coil induces a current in another that is in series with it. Would the direction of the induced current change if the current falls? With Lenz's law the induced current would oppose the current of the first coil but what would happen to the induced current if the switch...
  49. C

    What Determines the Direction of Induced Current in a Parallel Coil Setup?

    Homework Statement P and Q are two coils arranged in parallel to each other and coaxially. Q is connected in series with a cell, a closed switch S and a rheostat. Determine the direction of the current in P when: the switch S is opened. Homework Equations Lenz's Law: The direction of the...
  50. N

    Investigating Induced Current in Circular Coils

    If I have a top view of two circular coils of conducting wire lying on a flat surface, what is the direciton of induced current that appears in the smaller coil when the switch in the larger coil is closed? I'm trying to figure out: 1.) which direction the induced current would flow through...
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