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Chapter 30

Electromagnetic Induction

Induction
Induction
An emf is induced when the magnetic field in a coil is changed by pushing a bar magnet into or out of the coil. emfs of opposite signs are produced by ...
Faraday's Law
Faraday's Law
Faraday's law state that the induced emf is the negative change in the magnetic flux per unit of time. Any change in the magnetic field or change in ...
Lenz's Law
Lenz's Law
The direction in which the induced emf drives the current around a wire loop can be found through the negative sign. However, it is usually easier to ...
Motional Emf
Motional Emf
Magnetic flux depends on three factors: the strength of the magnetic field, the area through which the field lines pass, and the field's orientation ...
Faraday Disk Dynamo
Faraday Disk Dynamo
A Faraday disk dynamo is a DC generator, producing an emf that is constant in time. It consists of a conducting disk that rotates with a constant angular ...
Induced Electric Fields
Induced Electric Fields
The fact that emfs are induced in circuits implies that work is being done on the conduction electrons in the wires. What can possibly be the source of ...
Induced Electric Fields: Applications
Induced Electric Fields: Applications
An important distinction exists between the electric field induced by a changing magnetic field and the electrostatic field produced by a fixed charge ...
Eddy Currents
Eddy Currents
Since eddy currents occur only in conductors, magnets can separate metals from other materials. For example, in a recycling center, trash is dumped in ...
Displacement Current
Displacement Current
Ampère's law, in its usual form, does not work in places where the current changes with time and is not steady. Thus, Maxwell suggested including ...
Significance of Displacement Current
Significance of Displacement Current
A displacement current is analogous to a real current in Ampère's law, participating in Ampère's law the same way as the usual ...
Electromagnetic Fields
Electromagnetic Fields
Electric fields generated by static charges, often referred to as electrostatic fields, are characteristically different from electric fields created by ...
Maxwell's Equation Of Electromagnetism
Maxwell's Equation Of Electromagnetism
James Clerk Maxwell (1831–1879) was one of the major contributors to physics in the nineteenth century. Although he died young, he made major ...
Symmetry in Maxwell's Equations
Symmetry in Maxwell's Equations
Once the fields have been calculated using Maxwell's four equations, the Lorentz force equation gives the force that the fields exert on a charged ...
Ampere-Maxwell's Law: Problem-Solving
Ampere-Maxwell's Law: Problem-Solving
A parallel-plate capacitor with capacitance C, whose plates have area A and separation distance d, is connected to a resistor R and a battery of voltage ...
Differential Form of Maxwell's Equations
Differential Form of Maxwell's Equations
James Clerk Maxwell (1831–1879) was one of the significant contributors to physics in the nineteenth century. He is probably best known for having ...
Electric Generator: Alternator
Electric Generator: Alternator
Electric generators induce an emf by rotating a coil in a magnetic field. A simple alternator is an AC generator that creates electrical energy that ...
DC Generator
DC Generator
An alternator converts mechanical energy into electrical energy that varies sinusoidally, resulting in AC current. Meanwhile, a DC generator converts ...
Back EMF
Back EMF
Generators convert mechanical energy into electrical energy, whereas motors convert electrical energy into mechanical energy. A motor works by sending a ...
Magnetic Damping
Magnetic Damping
Eddy currents can produce significant drag on motion, called magnetic damping. For instance, when a metallic pendulum bob swings between the poles of a ...
Superconductor
Superconductor
A substance that reaches superconductivity, a state in which magnetic fields cannot penetrate, and there is no electrical resistance, is referred to as a ...
Types Of Superconductors
Types Of Superconductors
A superconductor is a substance that offers zero resistance to the electric current when it drops below a critical temperature. Zero resistance is not the ...
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