Inductive Reactance Electronics Inductors in AC Circuits Inductance

Inductive Reactance Electronics

Inductors in AC Circuits

Inductance n n n Inductance opposes a change in current. Inductors create a voltage that opposes the current. Counter EMF(voltage) v L

Inductance n n 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 = Ip 2πf. L Vp/Ip= 2πf. L R = 2πf. L Inductive Reactance XL = 2πf. L L is an Active Component

n Calculate the maximum current in a coil which has an inductance of 3 m. H. The frequency is 60 Hz. The maximum voltage across the coil is 6 V. L=3 m. H f=60 Hz XL = 2πf. L XL = 2π(60 Hz)(. 003 H) XL = 1. 13Ω E=6 V I = E/XL I = 6 V/1. 13Ω I = 5. 3 A

Inductive/Resistive Circuit n n 90° Phase Shift caused by Inductor Impedance, Z, is calculated by adding XL and R vectorially. XL Z R

n What is the impedance of a 100 m. H choke in series with a 470Ω resistor with a 12 V, 60 Hz applied across them? What is the phase angle between voltage and current? L=100 m. H f=60 Hz R=470Ω E=12 V XL = 2πf. L XL = 2π(60 Hz)(. 1 H) XL = 37. 7Ω

XL Z R

Current Voltage 4. 6° Inductance in AC

Inductance in AC Circuits

Capacitor Values 1 m. F = 1 X 10 -3 F 1μF = 1 X 10 -6 F 1 n. F = 1 X 10 -9 F 1 p. F = 1 X 10 -12 F

RLC Circuits

RLC Circuits n 90° Phase Shift caused by Inductor n -90° Phase Shift caused by Capacitor XL XC Z R

Xc = 1/(2πf. C) Xc = 1/(2π(60)(1. 5 X 10 -6) Xc = 1768Ω XL = 2πf. L XL = 2π(60)(0. 65) XL = 245Ω XL XC ZR �� = -81° ICE – Current leads Voltage by 81°

Resonance n n The frequency where XL = XC The Circuit becomes a purely resistive circuit Xc = 1/(2πf. C) XL = 2πf. L Xc = X L 1/(2πf. C) = 2πf. L 1/(4π2 CL) = f 2 =f

=f 161 Hz= f

Worksheet Lab 2 -6 Capacitors In AC Circuits Problems

Reactance Test Classwork n n Lab 7, Book 2 – Capacitive Reactance Worksheets n n n n Lab Lab } 2 -5 2 -6 2 -8 2 -9 2 -11 2 -12 2 -13 Due the day of the test!!