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This course includes Motion, Oscillations, waves and propagation, Electric Charge and Coulomb Law, Electric Field, Electric Potential, Capacitors and Dielectric, Current and Resistance, AC and DC, Magnetic fields, Ampere Law and Faraday law, Maxwell equations and Traveling waves. This file includes: Inductance, Property, Electromagnetic, Field, Energy, Characteristic, Electrical, Henry, Ampere, Magnetic, Conductor
Typology: Slides
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Inductance
“Inductance is the property of a circuit by which energy is stored in the form of an electromagnetic field".
Inductance is the characteristic of an electrical conductor that OPPOSES CHANGE in CURRENT
The symbol for inductance is L and the basic unit of inductance is the HENRY (H). One henry is equal to the inductance required to induce one volt in an inductor by a change of current of one ampere per second.
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Inductance
4
Inductance
5
Inductance
7
If ΦB is the magnetic flux through each turn of the coil
N is the number of turns of coil
The emf according to Faraday’s law can be given as
From equations 2 and 4
8
Integrating with respect to time
current “I” like capacitance is independent of charge “q” but depends upon the geometry of the device and the magnetic flux linkages i.e. NΦB
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Where μo is the permeability of free space
n, is the number of turns per unit length
i, is the current passing through the coils
The number of flux linkages in the length l is
NΦB = nl (BA) (8)
Substitute equations 7 in equation 8
NΦB = μon^2 l i A (9)
Substitute equation 9 in 6
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http://www.ndt-ed.org/EducationResources/CommunityCollege/EddyCurrents/Physics/circuitsphase.htm
The magnetic field in a toroid is
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b
b
b
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The inductance of the toroid can be written from equations 6 and 12
Inductance only depends on the geometry of toroid
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The inductor with no magnetic material has magnetic field Bo, while the inductor with magnetic material has magnetic field B
The inductance of an inductor with magnetic material can be given as
L = KmLo
Inductance of solenoid with magnetic substance of permeability constant Km is
L = Km μon^2 l A
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Three types of magnetic materials
Paramagnetic
Diamagnetic
Ferromagnetic
The permeability constant of paramagnetic and diamagnetic doesn't differ from 1 , thus by inserting these two types of materials the magnetic field almost remains same as with out materials
The permeability constant for ferromagnetic materials about is 103 to 104 , thus the inductance of an inductor filled with ferromagnetic materials increases
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A similar rise and fall of current occurs by inserting an emf source in a circuit containing inductor L and resistor R
If the inductor were not present the current would rise
appears in the circuit, which according to Lenz’s law opposes the increase in the current
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As long as the inductor is there in the circuit, the current, in the resistor depends upon the two emfs, one from battery
that’s why the current in the circuit rises exponentially
