Electromagnetic Induction Flashcards

1
Q

EMI

A

Phenomenon of production of induced EmF due to which magnetic Flux linked with a closed circuit

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2
Q

Faraday’s law

A

Magnitude of induced emf is equal to time rate of change of magnetic Flux linked with thr closed circuit
E = -Ndø/dt

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3
Q

Flux can be varied by

A

Changing A,B or ø

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4
Q

Magnetic flux

A

Total no of field lines crossing the surface normally
Ø(B) = B.A

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5
Q

Flux unit

A

Weber

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6
Q

Gauss’s law of magnetism

A

Total magnetism Flux throug hany closed system is 0
Ø(b) = sigma B.A = 0

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7
Q

Lenz’s law

A

Polarity of induced emf is such that it tends to produce a current which opposes change in Flux that produced it

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8
Q

When fluc changes from Øa to Øb in time t, avg Emf E=

A

E = -N(Øb-Øa)/t

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9
Q

Motional EMF

A

Emf induced across the ends of a conductor due to its motion in B

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10
Q

Motional emf E=

A

BlV where dx/dt = -V in decreasing dir of x

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11
Q

Motionless emf from Lorentz force & energy consideration

A

E = VBl

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12
Q

Motional emf I =

A

BlV/R

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13
Q

Motional emf F =

A

B²l²V/R

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14
Q

Motional emf P =

A

FV = B²l²V²/R = powerloss[P(j)]

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15
Q

Mechanical energy is converted to

A

Electrical energy then to thermal energy. So energy I’d conserved

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16
Q

Inductance

A

Phenomenon of production of induced emf in a coil by changing current through itself or neighbouring coil

17
Q

Inductance fm

A

Nø = KI where K is inductance

18
Q

Self Inductance + fm

A

Phenomenon of inducing EMF in a coil by changing I through itself
NØ = LI

19
Q

Self Inductance by Faraday’s law

A

E = -LdI/dt
-ve sign is because self induced emf opposes change in current through itself(back emf)

20
Q

Self Inductance of a long solenoid

A

L = myu°N²/l pi r²

21
Q

Self Inductance depends on:

A

N²(turns)
Area
Myu

22
Q

Slope of Ø-I graph gives

A

Self inductance

23
Q

Mutual inductance + fm

A

Phenomenon os inducing emf in a coil by changing current through te neighboring coil
NØ = mI

24
Q

Emf by faraday’s law for mutual inductance

A

E = -mdI/dt
-ve as Ø opposes emf

25
Mutual inductance of 2 long solenoids
m = myu°n1n2L pi r²
26
Mutual inductance depends on
M prop N1N2(Turns) M prop A (Area) M prop 1/l distance btw solenoids Relative orientation changes as we rotate it
27
Inductive coupling
When I flows through 2 nearby coils simultaneously, Flux linked with 1 coil will be sum of fluxes which exists independently E1 = -LdI1/dt - MdI2/dt N1Ø1/I2 = N2Ø2/I1
28
Coefficient of coupling k of 2 coils
K = m/(L1L2)½
29
Energy stored in an inductor
E = ½LI²
30
AC generator
Converts mechanical energy to electrical energy Principle: change in Flux induces emf in it
31
AC generator emf
E = E°sinwt(E°=wNBA) E° = amplitude of induced emf
32
Alternating emf & alternating current
Direction of induced emf and current varies periodically with time E = E°sin(2pi nyu t)
33
Factors on which mutual inductance depends on
N Area Distance btw solenoids(inversely) Relative orientation