If it is decreasing, the induced field acts in the direction of the applied field to try to keep it constant. In the examples below, if the B field is increasing, the induced field acts in opposition to it. The induced magnetic field inside any loop of wire always acts to keep the magnetic flux in the loop constant. When an emf is generated by a change in magnetic flux according to Faraday’s Law, the polarity of the induced emf is such that it produces a current whose magnetic field opposes the change which produces it. In the animation above the ammeter (the instrument used to measure current) indicates when there is current in the conductor. The direction that the induced current flows is determined by the direction of the lines of force and by the direction the wire is moving in the field. One requirement for this electromagnetic induction to take place is that the conductor, which is often a piece of wire, must be perpendicular to the magnetic lines of force in order to produce the maximum force on the free electrons. The current is said to be induced in the conductor by the magnetic field. This is called induction because there is no physical connection between the conductor and the magnet. This process of generating current in a conductor by placing the conductor in a changing magnetic field is called induction. is only produced while the flux is changing.įor example, consider two coils as shown in Following Figure.Ĭurrent is produced in a conductor when it is moved through a magnetic field because the magnetic lines of force are applying a force on the free electrons in the conductor and causing them to move. (b) By changing the magnitude of the source of magnetic flux. (a) moving the coil or the source of flux relative to each other or This effect was first observed and explained by Ampere and Faraday between 18. If magnetic flux through a coil is altered then an e.m.f. Around 1830 to 1832, Joseph Henry made a similar discovery, but did not publish his findings until later. Michael Faraday is generally credited with the discovery of induction in 1831 though it may have been anticipated by the work of Francesco Zantedeschi in 1829. This process of electromagnetic induction, in turn, causes an electrical current, it is said to induce the current. unit is the weber (Wb).Įlectromagnetic induction (or sometimes just induction) is a process where a conductor placed in a changing magnetic field (or a conductor moving through a stationary magnetic field) causes the production of a voltage across the conductor. Magnetic Flux is defined as the product of the magnetic flux density and the area normal to the field through which the field is passing. Induction can produce electricity (in coils), heat (in ferrous metals), or waves (in a radio transmitter).įinally, it is referring to the phenomenon where an emf is induced when the magnetic flux linking a conductor change. Electromagnetic induction is when an electromagnetic field causes molecules in another object to flow. This process of generating current in a conductor by placing the conductor in a changing magnetic field is called induction.Įlectromagnetic induction is the production of a potential difference (voltage) across a conductor when it is exposed to a varying magnetic field. The magnetic field disappears when the current is turned off. To study the phenomenon of Electromagnetic InductionĪn electromagnet is a type of magnet in which the magnetic field is produced by electric current.
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