Transcript Electric Force - Parkland College

AC Circuits
Resistors behave the same in an AC circuit
V
Vrms=Irms R
R
The voltage across a capacitor lags the current.
• Vrms = Irms XC
• Capacitive Reactance
• XC = 1/(2πfC) (Ω)
What is the rms current in a circuit with a 20microF
capacitor connected to a 120V AC source at 60Hz?
V=120V
F=60Hz
C = 20μF
The voltage across an inductor leads the current.
• Vrms = Irms XL
• Inductive Reactance
• XL = 2πfL (Ω)
What is the rms current in a circuit with a 10mH
inductor connected to a 120V AC source at 60Hz?
V=120V
F=60Hz
L=10mH
Putting them all together (LRC)
R
V=120V
F=60Hz
L
VR=I R
VC= I XC
VL= I XL
C
Vtot = I Z
(Impedance)Z= √R2 + (XC – XL)2
In the LRC circuit below:
1)what is the impedance 2) what is the current?
R = 100 Ω
V=120V
F=60Hz
L=10mH
C = 20μF
Phase Angle
Is the Voltage leading or lagging the current?
• If XC > XL The voltage is lagging the current
• If XC < XL The voltage is leading the current
• Tan φ = (XL – XC) /R
R = 100 Ω
V=120V
F=60Hz
L=10mH
C = 20μF
Power
P = Irms Vrms Cos φ (W)
• What is the power consumed by this circuit?
R = 100 Ω
V=120V
F=60Hz
L=10mH
C = 20μF