Transcript Impedance

Impedance
is the measure of the opposition that a circuit presents
to the passage of a current when a voltage is applied. In
quantitative terms, it is the complex ratio of the voltage
to the current in an alternating current (AC) circuit
Resistance

Resistance affects flow of current by opposing the
flow of electrons in a ckt
Inductance

Coil with wire wound around it

Opposes any change in current flow


It can not prevent the current from rising or falling
but it will OPPOSE any rise or fall
Current in ac ckts is constantly changing any
inductance in that ckt will oppose this change
Capacitance in A.C. Ckt

Made of 2 plates of conducting material

Constantly charged and discharged due to sine wave changes


The polarity of the voltage across the capacitor will be opposite
of the supply voltage
Therefore it opposes the supply voltage and will result in a
lower net voltage which cause the current to be lower
Capacitance in A.C CKT


Capacitance affects the current in the ckt by
opposing a change in voltage
Capacitance cannot prevent the voltage from rising
or falling but it will oppose the rise or fall
Summary A.C Resistance

Impedance measure in ohms (Z)

Inductive reactance in ohms (XL)

Capacitance reactance in ohms (XC)

Impedance includes




Resistance
Inductive Reactance
Capacitive Reactance
All measure in ohms
Summary A.C Resistance


Ohms law now becomes
Z is the total opposition to current flow in ac ckts
measured in ohms
Impedance (Z)
Total Current Limiting Effect
Caused By
Resistance
(R)
Limits current by oppising
flow of electrons
Inductive
Reactance(XL)
Capacitive
Reactance(Xc)
Caused by Inductance
Caused by Capacitance
Limits current by opposing
flow of current
Limits current by opposing
flow of voltage