Home Chapter 21 Objectives

# Objectives

After studying the material of this chapter, the student should be able to:
1. Determine the magnitude of the magnetic flux through a surface of known area, given the strength of the magnetic field and the angle between the direction of the magnetic field and the surface.
2. Write a statement of Faraday's law in terms of changing magnetic flux. Use Faraday's law to determine the magnitude of the induced emf in a closed loop due to a change in the magnetic flux through the loop.
3. Use Faraday's law to determine the magnitude of the induced emf in a straight wire moving through a magnetic field.
4. State Lenz' law and use Ohm's law and Lenz's law to determine the magnitude and direction of the induced current.
5. Explain the basic principle of the electric generator. Determine the magnitude of the maximum value of the induced emf in a loop which is rotating at a constant rate in a uniform magnetic field.
6. Explain how an eddy current can be produced in a piece of metal. Also, describe situations in which eddy currents are beneficial and situations in which they must be eliminated.
7. Explain how a transformer can be used to step up or step down the voltage. Apply the equations which relate number of turns, voltages, and currents in the primary and secondary coils to solve transformer problems.
8. Explain what is meant by mutual inductance and self inductance. List the factors which determine the self inductance of a solenoid. State the SI unit for inductance.
9. Write the equations for the average induced emf in a solenoid in which the current is changing at a known rate.
10. Write the equation for the energy stored in an inductor's magnetic field and also for the energy stored per unit volume, i.e., the energy density.
11. Write the equation for the voltage across the inductor as a function of time after the inductor is connected to the source of emf in an LR circuit. Graph the current as a function of time after the initial connection is completed. Write the equation for the voltage across the inductor as a function of time if the inductor is disconnected from the source of emf and discharged. Graph the current as a function of time after the discharge is initiated.
12. Distinguish between resistance, capacitive reactance, inductive reactance, and impedance in an LR or LRC circuit. Calculate the reactance of a capacitor and/or inductor which is connected to a source of known frequency.
13. Use a phasor diagram to determine the phase angle and total impedance for an LR, LC, or LRC circuit.
14. Determine the rms current and power dissipated in an LRC circuit. Determine the voltage drop across each circuit element and the resonant frequency of the circuit.