Part 32 Inductance .


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Chapter 32 Inductance. PHYS 2326-21. Concepts to Know. Self Induction Mutual Inductance Inductors Magnetic Field Energy RL Circuit LC Circuit LRC Circuit. Self Induction. Must distinguish between emf from sources like a battery and induced emf from changing magnetic fields.
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Slide 1

Section 32 Inductance PHYS 2326-21

Slide 2

Concepts to Know Self Induction Mutual Inductance Inductors Magnetic Field Energy RL Circuit LC Circuit LRC Circuit

Slide 3

Self Induction Must recognize emf from sources like a battery and instigated emf from changing attractive fields

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Mutual Inductance Magnetic flux variety in one circuit can bring about an attractive flux variety in another circuit. Take note of this can be by expectation or unintentionally. By goal, one can have a transformer By mishap, one transfer may bring about another hand-off to close or open. alternately commotion to be infused in one circuit by another

Slide 5

Mutual Inductance emf 2 = - N 2 d Φ 12/dt = - N 2 d(M 12 I 1/N 2 )/dt = - M 12 dI 1/dt , so emf 1 = - M 21 dI 2/dt Note that likewise M 12 = M 21 = M That is a current in curl 1 creates current in loop 2 and a current in curl 2 produces a current in loop 1

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Inductor An inductor is a circuit component that principally has extensive inductance It can be a solenoid valve, or hand-off or even simply a segment proposed to give inductance to a circuit to some reason Inductors are liable to Lenz\'s law which expresses that with a changing attractive field, there will be a move made to contradict that change

Slide 7

Magnetic Field Energy Given a connected emf over an inductor in arrangement with a resistance,

Slide 8

Transformer A transformer is two curls with aggregate common acceptance Read Chapter 33.8

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Permeability Ampere\'s law connected to a toroid Note that the attractive field B relies on μ o the porousness of free space. This is for the zone in the torus that the twisting circumvents What happens if it\'s not a vacuum? Most transformers and solenoids have metal centers in the curls

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Permeability Note this doesn\'t appear to try and be in this reading material In an indistinguishable idea from with dielectrics for capacitors there is an attractive equal to the dielectric steady K m = B/B o = relative porousness Note however that K for dielectrics ran from 1 for a vacuum upwards to ?? K m is 1 for a vacuum, > 1 for paramagnetic materials, somewhat littler than 1 for diagmagnetic materials and >> 1 for ferromagnetic materials

Slide 11

Permeability μ = μ o K m is the porousness of a material

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Example 1 Tesla loop has N1 turns along length l of an empty tube and a second curl of N2 what is a) the common inductance b) if N1=10,000 and N2 = 100, l = 1m, sweep 1cm what is the estimation of M? c) if a radio recurrence of 1000 KHz is sent through loop 2 so present sways with plentifulness of 100ma what is the normal attractive flux through coil1 d)max current through coil1 e)max initiated emf in coil1 f)back emf in curl 1?

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Example 1 M = N 2 Φ B2/I 1 , Φ B2 = Φ B1 =B 1 An A = π r 2 = 3.14(0.01)^2 = 0.000314 m 2 B 1 = μ o N 1 I 1/l substituting for B 1 M = ( μ o N 1 I 1/l ) N 2 A/I 1 = μ o N 2 N 1 An I 1/l b) M = 3.946 E - 4 H c) max flux? I 2 = I o sin ω t , ω = 2 π f (rakish freq.)=6.28E+6 revamping M, Φ B2 = Φ B1 = M I 2/N 2 = (3.946E-4)(0.1)/(100) = 3.948E-7 Wb

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Example 1 d) loop 1 current I 1 = I 2 N 2/N 1 = (0.1)(100)/(10,000) = 1.0 E-3A e) emf 1 = - M dI 2/dt , I 2 = I o sin ω t d I 2/dt = I o ω cos ω t emf 1 = - M I o ω cos ω t emf 1max = M I o ω = (3.948E-4)(0.1)(6.28E+6) = 248 V f) emf 2max = emf 1max N 2/N 1 =(248)(100/10,000) = 2.48 V

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Example 2 an) Inductance of a long solenoid length l and range A with N turns? b)if 2m long 2cm range and 2000 turns? c) if current diminished from 4A to 0 in 2 microseconds what is extent and heading of the self prompted emf ? d) what is the vitality put away in the solenoid toward the start of the 2 microsecond interim? e) How much electrical power is dispersed amid this time?

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Example 2 inductance Substituting for B in L

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b) Inductance esteem A = 1.257E-3 L = (1.2566E-6)(2000)^2(1.257E-3)/2.0 = 3.159E-3 H c) emf? emf = (3.159E-3)(4-0)/(2.0E-6) = 6318V in course of current attempting to stop handle fall by attempting to look after current

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d) Energy? U1 = (1/2) (3.158E-3)(4)^2 = 2.52E-2 Joules e) Power P = (2.52E-2)/(2E-6) = 12,632 W why so high? It\'s additionally about planning as well

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RL Circuits Review 32.2

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LC Circuits Study Chapter 32.5 Given a capacitor and an inductor at time t=0 with the capacitor being associated in arrangement to the inductor with Qmax charge on it there will be a swaying. On the off chance that no resistance is there to disperse the vitality, it will keep on oscillating

Slide 21

RLC Circuit Study Chapter 32.6 The contrast between a LC and RLC circuit – other than resistance exists in all circuits is that R is a dissipative component that retains vitality as present streams

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