Induced current Definition and 202 Threads

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

    B A question about induced current in LC circuits

    Let's say we have an LC circuit and we begin with the capacitor fully charged, it then starts discharging, and currents begins to flow in the circuit, and a magnetic field is generated in the inductor because of the current flowing through it. My question is, why is the magnetic field in this...
  2. Grizzly_1

    B Confusing diagram of a rotating coil in a magnetic field

    Hello all, I am currently studying for a physics a-level qualification in the UK, I use the AQA specification and I am having trouble understanding this image representing a scenario I found in my textbook. The first image in the three part diagram shows this rotating coil and to me, it makes...
  3. Ahmed1029

    I How do I find the Direction of an induced electric field?

    Faraday's law tell's you about the line intergal of the electric field, but you have to know the direction of the induced electric field first in order to properly apply it. How can I find its direction? Is it in the same direction as the induced current?
  4. L

    Maximum charge on the plates of a capacitor

    What I have done: The electromotive force due to Faraday's Law is: ##\mathcal{E}=-\frac{d\phi(\vec{B})}{dt}=\frac{d}{dt}(Ba^2)=a^2\frac{dB}{dt}=-10^{-4}V.## In the circuit, going around the loop in a clockwise fashion: ##\oint_{\Gamma}\vec{E}\cdot d\vec{l}=-\frac{d\phi(\vec{B})}{dt}\Rightarrow...
  5. J

    I How does a ferromagnet increase the inductance of an inductor?

    Inductance according to Faraday's law depends on a changing magnetic field. The magnitude of the induced emf depends on the magnitude of change in the magnetic field per change in time. Based on that, how does adding a constant magnetic field (a ferromagnet), increase the inductance of an inductor?
  6. L

    Force to apply to a loop moving away from a current-carrying wire

    What I have done: (1) ##\Phi(\vec{B})=\int_{S}\vec{B}\cdot d\vec{S}=-\frac{N\mu_0 il}{2\pi}\int_{s=h}^{s=h+l}\frac{ds}{s}=-\frac{\mu_0iNl}{2\pi}\ln(\frac{h+l}{h})## so ##\mathcal{E}=-\frac{d\phi(\vec{B})}{dt}=-\frac{\mu_0iNl^2v}{2\pi h(h+l)}## so...
  7. guyvsdcsniper

    Induced Current Direction in a Changing Magnetic Field

    So for the first question it is very straight forward. The magnetic field is going through the loop, increasing the flux through the loop. The induced current must flow clockwise in order to generate a field that goes through the loop in a downward direction to oppose the change.The second...
  8. jjson775

    Induced current in a wire loop embedded in a changing B-field

  9. D

    Problems about magnetic field, electromotive force, induced current

    Hi, I was practicing some problems on the magnetic field and the electromotive force, when I got stuck on these two exercises. Could you help me figure out how to proceed? In the first problem, I tried to find the magnetic field flux by multiplying the induced current for ∆t and R. Should I now...
  10. greg_rack

    Induced current in a square coil by a current-carrying wire

    I'll try to explain to you my thinking behind this problem... tell me if it's correct or not. In short, I have assumed the area enclosed between the wire and the left side of the coil to be ##A## in which is present a ##-\hat{z}## field, and noticed that the flux it generates must be canceled by...
  11. greg_rack

    Area-change-rate of a coil generating a given induced current

    I managed to solve this problem by writing the total E.M.F. as the sum of the one which would have been induced with only the magnetic field varying(and constant ##A##), and that with only the area varying(and constant ##B##). However, I got to this solution(which doesn't totally convince me)...
  12. greg_rack

    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...
  13. Gonzalo Lopez

    Motion Equation for a magnet on a spring

    Apart from the trivial elements of the motion equation (m z'' = -kz -mg), I am required to find the force produced by the Eddy currents induced by the moving magnet. To do so, I calculated the magnetic flux through the hole plate: For a magnet: Bz=μo m 4π. 2z^2−r^2/(z^2+r^2)^5/2 so Φ = a→ +∞...
  14. L

    Maximum Induced Voltage of an AC Generator

    I would like to ask a question about the induced voltage of an AC generator. So, according to a graph I found on Google, the maximum induced voltage is reached when the loop is parallel to the loop. (The graph shown below.) Then I was wondering, what if the loop is initially (when it is at 0...
  15. K

    DIY Electromagnetic Induction Experiment

    So I was watching this video containing DIY experiments on electromagnetic induction . At minute 4:45, the dude pretty much creates a transformer without using an iron core. He runs 30-50 kHz AC in a coil (forming the primary circuit) and then brings another coil with its ends attached to a...
  16. Kharrid

    Induced EMF in a moving Loop Conductor

    I am having trouble figuring out if the circular loop has an induced current. One explanation is ∫ E ds = -d Φ / dt. Since flux = B ⋅ A, a change in the magnetic field would require a change in the magnetic field, a change in the area, or change in direction of either vector. Since none of...
  17. F

    Calculating Current in Moving Rods: Exploring the Blv Rule and Faraday's Law

    Homework Statement: The rod is moving on a second rod with speed of v in the magnetic field perpendicular to rod. I know its resistance per meter. I am expected to omit megnetic field created by the current and resistance at the point where rods touch each other and calculate current. I...
  18. C

    Induced Current In a Tilted Square Inside and Outside a Solenoid

    Plot for the ring ^ Calculations for the Square ^ Plot for square without cosg on the outside calc ^ Plot for square with cosg on the outside calc ^ As can be seen the formulas for the square conductor do not connect at R, which I'm not sure if they should or if they should not as in this...
  19. T

    Finding the induced EMF in a solenoid-wire system

    I know that ##B = \mu n I## and ##\phi = B \pi R^2##. So with have ##d\phi / dt = \mu n \alpha \pi R^2##. But I don't know what to do with this? is this the answer? I don't think so but I don't know what to do after this.
  20. B

    Direction of the induced current from an OCR paper -- concept question

    I am not sure in which direction this induced current would be I am assuming you have to use the dynmo rule or the right hand rule as this is the induced current, and the soft iorn core will cause a force to be produced in the coil which causes the current. If so in which direction would the...
  21. R

    Reversing the Faraday effect to get an induced current

    Hi all! I was thinking if it is possible to revert the Faraday effect. If I have a magnetic field, it interacts with EM wave (light) by changing its polarisation. Can I got a variable magnetic field interacting with polarised light so that I can get induced current in a coil? I can understand...
  22. R

    Powering an LED via Induced Current

    Homework Statement As the title suggests, I have a school project where I’m supposed to design a hand shake flashlight using AWG 34 copper wire, a niobium cylindrical magnet, hard paper (sort of like cardboard), and a red LED. The goal’s to get the red LED to light. My teacher gave some hints...
  23. J

    The direction of induced current and magnetic field produced

    Homework Statement The figure below shows a small circular loop of wire in the plane of a long, straight wire that carries a steady current I upward. If the loop is moved from distance x_2 to distance x_1 from the straight wire, what will be the direction of the induced current in the loop and...
  24. K

    Induced Current in Stretched Square Loop: Flux Change and Direction?

    when a square loop is stretched to make a rectangular or circular loop(wire length remain same) in uniform magnetic field into the plane of paper what could be the direction of induced current. please share explanation as well
  25. Y

    Why does Fleming's right hand rule apply for induced current

    I know that the right hand rule applies for induced currents, and the left hand rule is for motors, but why? It doesn't seem to connect with any other physics laws and is very counter-intuitive that the current will flow in one direction rather than the opposite direction if both are...
  26. J

    Direction of induced current in the loop

    Homework Statement Homework EquationsThe Attempt at a Solution I am having a little doubt as to how to think of the moving electron as a current . I am considering the moving electron as a very tiny (infinitesimal ) current element . It is as if when the electron is at A , there is a very...
  27. Jan Berkhout

    How is current induced in the plasma in a tokamak?

    For a Year 12 Assignment I have to do a seminar on how magnetic fields are involved with a certain topic. I chose nuclear fusion energy production and specifically the tokamak. I understand that a toroidal magnetic field is created when a current is sent through a solenoid wrapped in a torus...
  28. 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...
  29. stevencarlover

    Induced Current Problem from the professor not in our textbook

    Homework Statement A long straight solenoid of cross-sectional area 400 cm^2 is wound with 10 turns of wire per centimeter, and the winding carry a current in the direction shown (downward). A small ring of radius 5.00 cm and resistance 0.300 ohms is placed at the center of the solenoid. If the...
  30. A

    Average power dissipation for induced current

    Homework Statement A wire shaped as a semi-circle of radius a rotates about the axis OO’ with a constant angular velocity ω in a uniform magnetic field with induction B (attached figure). The plane of the rectangular loop is perpendicular to the magnetic field direction. The total resistance of...
  31. M

    What Determines the Magnitude of Induced EMF?

    I understand the direction compnent of this question. But I don't understand where the magnitude of the induced current came from? I'm assuming faradays law wasn't used as there wasn't a change in magnetic field?
  32. M

    Why no induced current when these coils are stationary?

    These is there no induced current when the coils are stationary relative to each other? Isn't there still current (moving charges) in the the one on the left to cause a current in the one on the right when neither coil is moving?
  33. J

    Induced current in two connected loops

    Homework Statement Homework EquationsThe Attempt at a Solution Call the middle point where the two loops meet O . The induced EMF in the right wire should be anticlockwise and in the left loop should be clockwise . But there can be only one current in the wire . The induced EMF in the...
  34. M

    What is the Direction of Induced Current?

    Homework Statement The problem is simple, all I have to do is draw a voltage / time graph. The black ring is a conductor, its inner surface area is 0.01 m^2. The magnetic field points upward, B = 4T. 2. The attempt at a solution I understand what I have to do, but I'm getting the wrong +/-...
  35. astrocytosis

    Induced current in a loop of wire when straight wire is cut

    Homework Statement A square loop, side a, resistance R, lies a distance s from an infinite straight wire that carries current I (pointing to the right). Now someone cuts the wire, so I drops to zero. In what direction does the induced current in the square loop flow, and what total charge...
  36. S

    Direction of the induced current

    All sites and books give different answers for this question:( Homework Statement predict the polarity of the capacitor in the diagram below Homework Equations right hand thumb rule AB is capacitor The Attempt at a Solution The side facing south pole becomes south and north facing side...
  37. V

    Determining the direction of an induced current

    Homework Statement In Fig. 32-4( a) there is a uniform magnetic field in the + x-direction, with a value of B = 0.20 T. The circular loop of wire is in the yz-plane. The loop has an area of 5.0 cm2 and rotates about line CD as axis. Point-A rotates toward positive x-values from the position...
  38. G

    Direction of the induced current

    If there is a rotating wire in a constant magnetic field what is the direction of the induced current ? The problem is the direction of the area vector which is arbitrary, if it is parallel to the magnetic field the current will flow in a direction, if it is anti-parallel it will flow in the...
  39. V

    Induced current in an inductor

    I am struggling with the concept of induced current in a circuit consisting of an inductor and how that induced current establishes back EMF . Please see the page of the textbook attached . There is a circuit consisting of an inductor , a series resistance (not shown) and a battery ( not shown...
  40. A

    Induced current in magnet (what would happen if....)

    Homework Statement Homework Equations N/A The Attempt at a Solution [/B] I'm having a lot of trouble understanding induced magnetic fields. I was wondering if someone can explain it for me and confirm if I have the right answers? a) I labelled it [North | South], and the direction of the...
  41. C

    Induced current by moving bar magnet external to solenoid.

    Hi, I was wondering whether a bar magnet would induce a current if it was moving external to the solenoid, rather than within the coil. I see no reason why it wouldn't occur, but I've never seen it displayed or mentioned so I'm not sure. Thank you.
  42. D

    Exploring Induced Current in a Metal Coil

    Homework Statement The figure shows a metal coil labored as A. Heading torwards a region where a uniform static magnet field exists, poiting torwards the ground (hence X). The coil moves with the same constant velocity. As it enter the magnet field the coil will have an induced current in it...
  43. BrainMan

    Induced Current in a Coil with Changing Magnetic Field

    Homework Statement A 5.0-cm-diameter coil has 20 turns and a resistance of 0.50Ω. A magnetic field perpendicular to the coil is B=0.020t+0.010t^2, where B is in tesla and t is in seconds. Find an expression for the induced current I(t) as a function of time. Homework EquationsThe Attempt at a...
  44. P

    Building speakers, induction and induced current

    i made a speaker from a cup, a coil of wire and a magnet. I hooked up both of the ends of the wire to a headphone jack and it works. Albeit very low sound, but it works. Can you point me in the direction of some equations that will show me the most influential factors on how to make it louder...
  45. K

    Induced current in a moving bar on rails

    Homework Statement 2 movable conducting bars on a conducting rail with a uniform magnetic field heading inside the paper , what will happen to bar 2 if we move bar 1 to the left with a velocity v ? 3. The Attempt at a Solution i think that a current will be induced in bar 2 and pass to bar...
  46. L

    Induced current in a metal ring

    Homework Statement A metal ring with a radius of 10cm and resistance 0.1Ω passes through a delimited magnetic field, look at the photo posted below. The ring has a velocity of 5m/s, and the magnetic field has the field strength 0.4T. When the ring passes through the magnetic field, at some...
  47. Clara Chung

    Why Does Induced Current in a Solenoid Flow Left to Right?

    Homework Statement Homework EquationsThe Attempt at a Solution The answer of 2c is : Current through A to the left. But I think it is to the right. By I=V/R, a reduced resistance R results in an increase of current through solenoid X. By B=unI, an increase in current causes the magnetic flux...
  48. mikemartinlfs

    Electromagnetic Induction (Long straight wire above circulua

    Homework Statement A circular loop of wire is placed next to a long straight wire. The current I in the long straight wire is increasing. What direction is the current that's induced in the circular loop? Homework Equations The Attempt at a Solution I'm aware that the answer is clockwise...
  49. O

    Calculating Induced Current in a Coil Surrounding a Changing Current Solenoid

    Homework Statement A coil with 140 turns, a radius of 5.2 cm, and a resistance of 11.0 Ω surrounds a solenoid with 200 turns/cm and a radius of 4.5 cm. The current in the solenoid changes at a constant rate from 0 A to 2.0 A in 0.10 s. Calculate the magnitude and direction of the induced...
  50. Mzzed

    Voltages in an induced current

    I've been messing around with ampere's and faraday's laws as we have recently been applying them in undergrad level physics. I'm confused as to how voltage fits in with these laws when used for a solenoid inducing a current in a material placed inside the solenoid. I know that the induced...
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