PHYS 1112
Chapter 20 Problems

Chapter Objectives

  1. Define the magnetic flux through a closed loop.
  2. Describe how an emf can be induced in a closed loop.  Calculate the emf due to a changing magnetic flux through a closed loop.
  3. Calculate the emf that is induced in a closed loop due to motion.
  4. Describe how a generator works.
  5. Describe the role of an inductor in a d.c. circuit.  

Conceptual Questions

  1. A circular current loop is located in a uniform and constant magnetic field. Describe how an emf can be induced in the loop.
  2. How do magnetic storms on the Sun affect communications here on Earth?
  3. A small magnet with a large magnetic field is dropped down a piece of copper pipe. The magnet takes 4 seconds to fall 1 meter. Why?
  4. If the frequency in a series RLC circuit is doubled, what happens to the resistance, the inductive reactance, and the capacitive reactance?
  5. What is the impedance of an RLC circuit at the resonance frequency?
  6. Does a wire connected to a battery emit an electromagnetic wave?
  7. Will a transformer work with a d.c. current?

Problems

  1. A square loop 2.00 m on a side is placed in a magnetic field of strength 0.300 T. If the field makes an angle of 50.0 degrees with the normal to the plane of the loop, as in Figure 20.2, determine the magnetic flux through the loop.
  2. A 500-turn circular-loop coil 15.0 cm in diameter is initially aligned so that its axis is parallel to the Earth's magnetic field. In 2.77 ms, the coil is flipped so that its axis is perpendicular to the Earth's magnetic field. If a voltage of 0.166 V is thereby induced in the coil, what is the value of the Earth's magnetic field?
  3. Consider the arrangement shown in Figure 20.35 (slidable bar on rails in series with a resistor). Assume that R = 6.0 ohms and l = 1.2 m, and that a uniform 2.5 T magnetic field is directed into the page. At what speed should the bar be moved to produce a current of 0.50 A in the resistor?
  4. A 6.0 V battery is connected in series with a resistor and an inductor. The series circuit has a time constant of 600 microseconds, and the maximum current is 300 milliamps. What is the value of the inductance?
Solutions

If you find an error in these, or just have a comment, send an e-mail message to jpratte@kennesaw.edu