Physics
Faraday's Law
Faraday's Law states that a changing magnetic field induces an electromotive force (EMF) in a conductor. This phenomenon is the basis for the operation of generators and transformers. The law quantifies the relationship between the rate of change of the magnetic field and the induced EMF, providing a fundamental principle for understanding electromagnetic induction.
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10 Key excerpts on "Faraday's Law"
No longer available |Learn more- (Author)
- 2014(Publication Date)
- College Publishing House(Publisher)
____________________ WORLD TECHNOLOGIES ____________________ Chapter 9 Faraday's Law of Induction Faraday's Law of induction is a basic law of electromagnetism relating to the operating principles of transformers, inductors, and many types of electrical motors and generators. The law states that: The induced electromotive force (EMF) in any closed circuit is equal to the time rate of change of the magnetic flux through the circuit. Or alternatively: The EMF generated is proportional to the rate of change of the magnetic flux. History Electromagnetic induction was discovered independently by Michael Faraday and Joseph Henry in 1831; however, Faraday was the first to publish the results of his experiments. ____________________ WORLD TECHNOLOGIES ____________________ Faraday's disk In Faraday's first experimental demonstration of electromagnetic induction (August 1831), he wrapped two wires around opposite sides of an iron torus (an arrangement similar to a modern transformer). Based on his assessment of recently-discovered properties of electromagnets, he expected that when current started to flow in one wire, a sort of wave would travel through the ring and cause some electrical effect on the opposite side. He plugged one wire into a galvanometer, and watched it as he connected the other wire to a battery. Indeed, he saw a transient current (which he called a wave of electricity) when he connected the wire to the battery, and another when he disconnected it. Within two months, Faraday had found several other manifestations of electromagnetic induction. For example, he saw transient currents when he quickly slid a bar magnet in and out of a coil of wires, and he generated a steady (DC) current by rotating a copper disk near a bar magnet with a sliding electrical lead (Faraday's disk). Faraday explained electromagnetic induction using a concept he called lines of force.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- University Publications(Publisher)
____________________ WORLD TECHNOLOGIES ____________________ Chapter- 3 Faraday's Law of Induction Faraday's Law of induction is a basic law of electromagnetism relating to the operating principles of transformers, inductors, and many types of electrical motors and generators. The law states that: The induced electromotive force (EMF) in any closed circuit is equal to the time rate of change of the magnetic flux through the circuit. Or alternatively: The EMF generated is proportional to the rate of change of the magnetic flux. History Electromagnetic induction was discovered independently by Michael Faraday and Joseph Henry in 1831; however, Faraday was the first to publish the results of his experiments. ____________________ WORLD TECHNOLOGIES ____________________ Faraday's disk In Faraday's first experimental demonstration of electromagnetic induction (August 1831), he wrapped two wires around opposite sides of an iron torus (an arrangement similar to a modern transformer). Based on his assessment of recently-discovered properties of electromagnets, he expected that when current started to flow in one wire, a sort of wave would travel through the ring and cause some electrical effect on the opposite side. He plugged one wire into a galvanometer, and watched it as he connected the other wire to a battery. Indeed, he saw a transient current (which he called a wave of electricity) when he connected the wire to the battery, and another when he disconnected it. Within two months, Faraday had found several other manifestations of electromagnetic induction. For example, he saw transient currents when he quickly slid a bar magnet in and out of a coil of wires, and he generated a steady (DC) current by rotating a copper disk near a bar magnet with a sliding electrical lead (Faraday's disk). Faraday explained electromagnetic induction using a concept he called lines of force.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Orange Apple(Publisher)
________________________ WORLD TECHNOLOGIES ________________________ Chapter- 7 Faraday's Law of Induction Faraday's Law of induction is a basic law of electromagnetism relating to the operating principles of transformers, inductors, and many types of electrical motors and generators. The law states that: The induced electromotive force (EMF) in any closed circuit is equal to the time rate of change of the magnetic flux through the circuit. Or alternatively: The EMF generated is proportional to the rate of change of the magnetic flux. History Electromagnetic induction was discovered independently by Michael Faraday and Joseph Henry in 1831; however, Faraday was the first to publish the results of his experiments. ________________________ WORLD TECHNOLOGIES ________________________ Faraday's disk In Faraday's first experimental demonstration of electromagnetic induction (August 1831), he wrapped two wires around opposite sides of an iron torus (an arrangement similar to a modern transformer). Based on his assessment of recently-discovered properties of electromagnets, he expected that when current started to flow in one wire, a sort of wave would travel through the ring and cause some electrical effect on the opposite side. He plugged one wire into a galvanometer, and watched it as he connected the other wire to a battery. Indeed, he saw a transient current (which he called a wave of electricity) when he connected the wire to the battery, and another when he disconnected it. Within two months, Faraday had found several other manifestations of electromagnetic induction. For example, he saw transient currents when he quickly slid a bar magnet in and out of a coil of wires, and he generated a steady (DC) current by rotating a copper disk near a bar magnet with a sliding electrical lead (Faraday's disk). Faraday explained electromagnetic induction using a concept he called lines of force.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Academic Studio(Publisher)
________________________ WORLD TECHNOLOGIES ________________________ Chapter 7 Faraday's Law of Induction Faraday's Law of induction is a basic law of electromagnetism relating to the operating principles of transformers, inductors, and many types of electrical motors and generators. The law states that: The induced electromotive force (emf) in any closed circuit is equal to the time rate of change of the magnetic flux through the circuit. Or alternatively: The EMF generated is proportional to the rate of change of the magnetic flux. History Electromagnetic induction was discovered independently by Michael Faraday and Joseph Henry in 1831; however, Faraday was the first to publish the results of his experiments. Faraday's disk ________________________ WORLD TECHNOLOGIES ________________________ In Faraday's first experimental demonstration of electromagnetic induction (August 1831), he wrapped two wires around opposite sides of an iron torus (an arrangement similar to a modern transformer). Based on his assessment of recently-discovered properties of electromagnets, he expected that when current started to flow in one wire, a sort of wave would travel through the ring and cause some electrical effect on the opposite side. He plugged one wire into a galvanometer, and watched it as he connected the other wire to a battery. Indeed, he saw a transient current (which he called a wave of electricity) when he connected the wire to the battery, and another when he disconnected it. Within two months, Faraday had found several other manifestations of electromagnetic induction. For example, he saw transient currents when he quickly slid a bar magnet in and out of a coil of wires, and he generated a steady (DC) current by rotating a copper disk near a bar magnet with a sliding electrical lead (Faraday's disk). Faraday explained electromagnetic induction using a concept he called lines of force.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Academic Studio(Publisher)
________________________ WORLD TECHNOLOGIES ________________________ Chapter 13 Faraday's Law of Induction Faraday's Law of induction is a basic law of electromagnetism relating to the operating principles of transformers, inductors, and many types of electrical motors and generators. The law states that: The induced electromotive force (EMF) in any closed circuit is equal to the time rate of change of the magnetic flux through the circuit. Or alternatively: The EMF generated is proportional to the rate of change of the magnetic flux. History Electromagnetic induction was discovered independently by Michael Faraday and Joseph Henry in 1831; however, Faraday was the first to publish the results of his experiments. ________________________ WORLD TECHNOLOGIES ________________________ Faraday's disk In Faraday's first experimental demonstration of electromagnetic induction (August 1831), he wrapped two wires around opposite sides of an iron torus (an arrangement similar to a modern transformer). Based on his assessment of recently-discovered properties of electromagnets, he expected that when current started to flow in one wire, a sort of wave would travel through the ring and cause some electrical effect on the opposite side. He plugged one wire into a galvanometer, and watched it as he connected the other wire to a battery. Indeed, he saw a transient current (which he called a wave of electricity) when he connected the wire to the battery, and another when he disconnected it. Within two months, Faraday had found several other manifestations of electromagnetic induction. For example, he saw transient currents when he quickly slid a bar magnet in and out of a coil of wires, and he generated a steady (DC) current by rotating a copper disk near a bar magnet with a sliding electrical lead (Faraday's disk). Faraday explained electromagnetic induction using a concept he called lines of force.
eBook - PDF- Daniel Fleisch(Author)
- 2008(Publication Date)
- Cambridge University Press(Publisher)
3 Faraday’s law In a series of epoch-making experiments in 1831, Michael Faraday demonstrated that an electric current may be induced in a circuit by changing the magnetic flux enclosed by the circuit. That discovery is made even more useful when extended to the general statement that a changing magnetic field produces an electric field. Such ‘‘induced’’ elec-tric fields are very different from the fields produced by electric charge, and Faraday’s law of induction is the key to understanding their behavior. 3.1 The integral form of Faraday’s law In many texts, the integral form of Faraday’s law is written as I C ~ E d ~ l ¼ d dt Z S ~ B ^ n da Faraday ’ s law ð integral form Þ : Some authors feel that this form is misleading because it confounds two distinct phenomena: magnetic induction (involving a changing magnetic field) and motional electromotive force (emf) (involving movement of a charged particle through a magnetic field). In both cases, an emf is produced, but only magnetic induction leads to a circulating electric field in the rest frame of the laboratory. This means that this common version of Faraday’s law is rigorously correct only with the caveat that ~ E rep-resents the electric field in the rest frame of each segment d ~ l of the path of integration. 58 A version of Faraday’s law that separates the two effects and makes clear the connection between electric field circulation and a changing magnetic field is emf ¼ d dt Z S ~ B ^ n da Flux rule , I C ~ E d ~ l ¼ Z S @ ~ B @ t ^ n da Faraday ’ s law ð alternate form Þ : Note that in this version of Faraday’s law the time derivative operates only on the magnetic field rather than on the magnetic flux, and both ~ E and ~ B are measured in the laboratory reference frame. Don’t worry if you’re uncertain of exactly what emf is or how it is related to the electric field; that’s all explained in this chapter.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- The English Press(Publisher)
________________________ WORLD TECHNOLOGIES ________________________ Chapter- 1 Faraday's Law of Induction Faraday's Law of induction is a basic law of electromagnetism relating to the operating principles of transformers, inductors, and many types of electrical motors and generators. The law states that: The induced electromotive force (EMF) in any closed circuit is equal to the time rate of change of the magnetic flux through the circuit. Or alternatively: The EMF generated is proportional to the rate of change of the magnetic flux. History Electromagnetic induction was discovered independently by Michael Faraday and Joseph Henry in 1831; however, Faraday was the first to publish the results of his experiments. ________________________ WORLD TECHNOLOGIES ________________________ Faraday's disk In Faraday's first experimental demonstration of electromagnetic induction (August 1831), he wrapped two wires around opposite sides of an iron torus (an arrangement similar to a modern transformer). Based on his assessment of recently-discovered properties of electromagnets, he expected that when current started to flow in one wire, a sort of wave would travel through the ring and cause some electrical effect on the opposite side. He plugged one wire into a galvanometer, and watched it as he connected the other wire to a battery. Indeed, he saw a transient current (which he called a wave of electricity) when he connected the wire to the battery, and another when he disconnected it. Within two months, Faraday had found several other manifestations of electromagnetic induction. For example, he saw transient currents when he quickly slid a bar magnet in and out of a coil of wires, and he generated a steady (DC) current by rotating a copper disk near a bar magnet with a sliding electrical lead (Faraday's disk). Faraday explained electromagnetic induction using a concept he called lines of force.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Library Press(Publisher)
________________________ WORLD TECHNOLOGIES ________________________ Chapter- 2 Faraday's Law of Induction Faraday's Law of induction is a basic law of electromagnetism relating to the operating principles of transformers, inductors, and many types of electrical motors and generators. The law states that: The induced electromotive force (emf) in any closed circuit is equal to the time rate of change of th e magnetic flux through the circuit. Or alternatively: The EMF generated is proportional to the rate of change of the magnetic flux. History Electromagnetic induction was discovered independently by Michael Faraday and Joseph Henry in 1831; however, Faraday was the first to publish the results of his experiments. Faraday's disk ________________________ WORLD TECHNOLOGIES ________________________ In Faraday's first experimental demonstration of electromagnetic induction (August 1831), he wrapped two wires around opposite sides of an iron torus (an arrangement similar to a modern transformer). Based on his assessment of recently -discovered properties of electromagnets, he expected that when current started to flow in one wire, a sort of wave would travel through the ring and cause some electrical effect on the opposite side . He plugged one wire into a galvanometer, and watched it as he connected the other wire to a battery. Indeed, he saw a transient current (which he called a wave of electricity) when he connected the wire to the battery, and another when he disconnected it. Within two months, Faraday had found several other manifestations of electromagnetic induction. For example, he saw transient currents when he quickly slid a bar magnet in and out of a coil of wires, and he generated a steady (DC) current by rotating a copper disk near a bar magnet with a sliding electrical lead (Faraday's disk). Faraday explained electromagnetic induction using a concept he called lines of force.
eBook - PDF- David Halliday, Robert Resnick, Kenneth S. Krane(Authors)
- 2019(Publication Date)
- Wiley(Publisher)
In the next section, we give the mathematical basis for these effects. 34-2 FARADAY’S LAW OF INDUCTION Imagine that there are lines of magnetic field coming from the bar magnet of Fig. 34-1 and from the right-hand current loop in Fig. 34-2. Some of those field lines pass through the left-hand coil in both figures. As the magnet is moved in the situation of Fig. 34-1, or as the switch is opened or closed in Fig. 34-2, the number of lines of the magnetic field pass- ing through the left-hand coil changes. As Faraday’s experi- ments showed and as Faraday’s technique of field lines helps us visualize, it is the change in the number of field lines passing through a circuit loop that induces the emf in the loop. Specifically, it is the rate of change in the number of field lines passing through the loop that determines the induced emf. To make this statement quantitative, we introduce the magnetic flux B . Like the electric flux (see Section 27-3), the magnetic flux can be considered to be a measure of the number of field lines passing through a surface. In analogy with the electric flux (see Eq. 27-7), the magnetic flux through any surface is defined as (34-1) Here is an element of area of the surface (shown in Fig. 34-3), and the integration is carried out over the entire sur- face through which we wish to calculate the flux (for exam- ple, the surface enclosed by the loop in Fig. 34-1). If the magnetic field has a constant magnitude and direction over a planar area A, the flux can be written (34-2) where is the angle between the normal to the surface and the direction of the field. The SI unit of magnetic flux is the tesla meter 2 , which is given the name of weber (abbreviation Wb); that is, Inverting this relationship, we see that the tesla is equiva- lent to the weber/meter 2 , which was the unit used for mag- netic fields before the tesla was adopted as the SI unit.
eBook - PDF- Pierluigi Zotto, Sergio Lo Russo, Paolo Sartori(Authors)
- 2022(Publication Date)
- Società Editrice Esculapio(Publisher)
The appearance of a current is not, however, the main effect: if the circuit is opened in a whatever point, a voltage, independent of the opening position, is measured between the circuit extremities. The just described phenomenon is called electromagnetic induction. Its main effect is the appearance of an induced electromotive force E i in a circuit and, as a secondary effect, of an induced current, caused by the electromotive force that makes the free electrons move in the coil, if the circuit is closed. The magnitude of the induced electromotive force only depends on the time rate of change of the magnetic flux linked to the circuit. Experiments show that Faraday’s law (1791-1867) E i = − dΦ B dt , which states that whenever the flux of a magnetic field linked to a closed, or open in a point, circuit changes in time, an electromotive force E i , moment by moment equal to the sign in- verted derivative of the magnetic flux with respect to time, i.e. the opposite of the time rate of change of the magnetic flux, is generated, governs electromagnetic induction. 12.3 Lenz’s law The minus sign in Faraday’s law expresses Lenz’s law (1804-1865) which states that the direction of the electromotive force E i is such that it induces a current i which gen- erates, in its turn, an induced magnetic field B i whose flux linked to the circuit tends to compensate the flux change which generated it. In other words, the effect is such that it opposes the cause which produced it. Consider, for instance, the case of a moving magnet. The B field generated by the mag- net is not uniform, so, if the magnet moves towards the coil, its magnetic flux linked to it increases, while, if it moves away from the coil, the linked flux decreases.
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