PHYSICS 236 Topic Checklist
UNIT 3
At the end of each chapter make sure that you are familiar with all the listed topics and most importantly that you can do the homework problems associated with them.
Chapter 31: Electromagnetic Induction A changing magnetic field will create an electric field and electric potential difference.
q Faraday’s Law of Electromagnetic Induction The EMF induced in a circuit is equals the time rate of change of the magnetic flux through the circuit.
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q Motional EMF This is voltage that is induced in a conductor moving through a magnetic field.
q Lenz’s Law The polarity of induced EMF always opposes the flux change that induces it.
q Induced Electric Field forms closed loops that do not begin or end on charges.
q Generators convert mechanical energy into electrical energy by rotating a conductor in a magnetic field..
V=NABw sinwt
Chapter 32: Inductance
q Self Inductance Voltage is induced in a coil when the current in the coil changes.
q Inductance of a Coil
q Inductance of a Solenoid
q RL Circuits
q Magnetic Energy stored in an inductor carrying current.
q Magnetic Energy Density stored in the magnetic field.
q Mutual Inductance Changing magnetic flux in one circuit can induce EMF in a second near by circuit.
q LC Circuits: Oscillations
Chapter 33: Alternating Current Circuits are circuits driven by a sinusoidal source of EMF.
q RMS Values are the square root of the average of the square of a function. For sinusoidal voltages and currents:
q Resistors in an AC Circuit
ü I = V/R
ü Current and voltage are in phase
q Inductors in an AC Circuit
ü Reactance of an inductor: XL = 2pfL
ü I = V/XL
ü Voltage leads current by 90°
q Capacitors in an AC Circuit
ü Reactance of an capacitor: XC = 1/2pfC
ü I = V/XC
ü Voltage lags current by 90°
q Impedance is the combined effect of the resistance, inductance and capacitance. In a series circuit:
q The current and phase angle are
q Phasor Diagrams relate resistance, reactance and impedance and show the phase.
q Average Power in an AC Circuit
q Resonance The current and power are greatest if the source frequency matches the resonant frequency of the circuit.
q Quality Factor determines the bandwidth of the circuit.
q Low Pass and High Pass Filters
q Transformers Step up, step down, and impedance matching.
Chapter 34: Electromagnetic Waves are generated by accelerated charges.
q Wave Equation
q Sinusoidal Plane Waves
q Wavelength
q Speed of Electromagnetic Waves
q Energy in an Electromagnetic Wave The Poynting Vector represents the energy carried by the wave per second per unit area. The unit is W/m² and the direction is the direction of propagation of the wave.
q Energy Density (J/m3)
q Momentum and Radiation Pressure
q Electromagnetic Spectrum from radio to gamma rays.