Inductive Reactance and AC Circuits, Slides of Physics

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Inductive Reactance

Inertial Mass

Acceleration of water in a piperequires force to move a mass.

An inductor creates an emfproportional to a change incurrent.

•^

Magnetic field in the coil

The field acts as a mass thatreduces change in the current.

A )

v

i

L

v^ t

m

t

F^

tI t

L t V

^

Phase Shift



Voltage and current are not in phase through aninductor.

-^

Voltage leads current: ELI the ICE man

Ohm for Inductors

The amplitude of voltage andcurrent through an inductor arerelated.

The ratio gives an expressionlike Ohm’s law.

This is the

inductive reactance

•^

Measured in ohms

L

^ L

L

V

V

v i

X

L

L











0

0

v

0

sin 0

V t

V

v^ L







L V t L V i 





0

0

cos





Different Response

Inductors and capacitors reactdifferently with changes tofrequency.

•^

Resistors stay the same

Consider reactances that areequal at a frequency

•^

Capacitive reactance higherfor low frequency

-^

Inductive reactance higher forhigh freqency

Resistance vs Reactance

Resistance is measured inohms.

Resistance doesn’t depend onfrequency.

Resistance doesn’t affect thephase.

Reactance is measured inohms.

Reactance depends onfrequency.

•^

C

or

L

Reactance shifts the phase.

•^

ELI the ICE man

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