Download Inductors - Hingham Schools

Inductive Reactance
Electronics
Inductors in AC Circuits
Inductance



Inductance opposes
a change in current.
Inductors create a
voltage that opposes
the current.
Counter EMF(voltage)
v
L
Inductance


The Henry (symbol: H) is
the SI unit of inductance.
It is named after the
American physicist Joseph
Henry..
Current
Voltage
Capacitor in DC
ELI
E L I
Voltage
Inductance
Current
Voltage leads Current
in an
Inductive Circuit
Current
Voltage
Inductance in AC
Current
I = Ipsin(2πft)
Voltage
V = L di/dt
Ip-Peak Current
2π-Cycle
V = L d(Ipsin(2πft))/dt
f-frequency(Hz)
t-time(seconds)
V = L Ip(2πf)cos(2πft)
Vp = Ip(2πf)L
Vp = Ip2πfL
Vp/Ip= 2πfL
R = 2πfL
Inductive Reactance
XL = 2πfL
L is an Active Component

Calculate the maximum current in a coil which
has an inductance of 3 mH. The frequency is
60Hz. The maximum voltage across the coil is
6 V.
L=3mH
f=60Hz
XL = 2πfL
XL = 2π(60Hz)(.003H)
XL = 1.13Ω
E=6V
I = E/XL
I = 6V/1.13Ω
I = 5.3A
Inductive/Resistive Circuit


90° Phase Shift caused by Inductor
Impedance, Z, is calculated by adding
XL and R vectorially.
XL
Z
R

What is the impedance of a 100mH choke in
series with a 470Ω resistor with a 12V, 60Hz
applied across them? What is the phase angle
between voltage and current?
L=100mH
f=60Hz R=470Ω E=12V
XL = 2πfL
XL = 2π(60Hz)(.1H)
XL = 37.7Ω
XL
Z
R
Current
Voltage
4.6°
Inductance in AC
Inductance in AC Circuits
Capacitor Values
1mF = 1 X 10-3F
1μF = 1 X 10-6F
1nF = 1 X 10-9F
1pF = 1 X 10-12F
RLC Circuits
RLC Circuits

90° Phase Shift caused by Inductor

-90° Phase Shift caused by Capacitor
XL
XC
Z
R
Xc = 1/(2πfC)
Xc = 1/(2π(60)(1.5X10-6)
Xc = 1768Ω
XL = 2πfL
XL = 2π(60)(0.65)
XL = 245Ω
XL
XC
ZR
𝚹 = -81°
ICE – Current leads Voltage by 81°
Resonance


The frequency where XL = XC
The Circuit becomes a purely resistive
circuit
Xc = 1/(2πfC)
XL = 2πfL
Xc = XL
1/(2πfC) = 2πfL
1/(4π2CL) = f2
=f
=f
161 Hz= f
Worksheet Lab 2-6
Capacitors
In
AC Circuits
Problems
Reactance Test Classwork


Lab 7, Book 2 – Capacitive Reactance
Worksheets







Lab
Lab
Lab
Lab
Lab
Lab
Lab
2-5
2-6
2-8
2-9
2-11
2-12
2-13
Due the day
of the test!!