Chapter 20

1. Chapter 20

2. A square conductor moves through a uniform magnetic field. Which of the figures shows the correct charge distribution on the conductor?

3. A square conductor moves through a uniform magnetic field. Which of the figures shows the correct charge distribution on the conductor?

4. Is there an induced current in this circuit? If so, what is its direction? • Yes, clockwise • Yes, counterclockwise • No

5. Is there an induced current in this circuit? If so, what is its direction? • Yes, clockwise • Yes, counterclockwise • No

6. A square loop of copper wire is pulled through a region of magnetic field. Rank in order, from strongest to weakest, the pulling forcesthat must be applied to keep the loop moving at constant speed. • F2 = F4 > F1 = F3 • F3 > F2 = F4 > F1 • F3 > F4 > F2 > F1 • F4 > F2 > F1 = F3 • F4 > F3 > F2 > F1

7. A square loop of copper wire is pulled through a region of magnetic field. Rank in order, from strongest to weakest, the pulling forcesthat must be applied to keep the loop moving at constant speed. • F2 = F4 > F1 = F3 • F3 > F2 = F4 > F1 • F3 > F4 > F2 > F1 • F4 > F2 > F1 = F3 • F4 > F3 > F2 > F1

8. A current-carrying wire is pulled away from a conducting loop in the direction shown. As the wire is moving, is there a cw current around the loop, a ccw current or no current? • There is a clockwise current around the loop. • There is a counterclockwise current around the loop. • There is no current around the loop.

9. A current-carrying wire is pulled away from a conducting loop in the direction shown. As the wire is moving, is there a cw current around the loop, a ccw current or no current? • There is a clockwise current around the loop. • There is a counterclockwise current around the loop. • There is no current around the loop.

10. A conducting loop is halfway into a magnetic field. Suppose the magnetic field begins to increase rapidly in strength. What happens to the loop? • The loop is pushed upward, toward the top of the page. • The loop is pushed downward, toward the bottom of the page. • The loop is pulled to the left, into the magnetic field. • The loop is pushed to the right, out of the magnetic field. • The tension is the wires increases but the loop does not move.

11. A conducting loop is halfway into a magnetic field. Suppose the magnetic field begins to increase rapidly in strength. What happens to the loop? • The loop is pushed upward, toward the top of the page. • The loop is pushed downward, toward the bottom of the page. • The loop is pulled to the left, into the magnetic field. • The loop is pushed to the right, out of the magnetic field. • The tension is the wires increases but the loop does not move.

12. The potential at a is higher than the potential at b. Which of the following statements about the inductor current I could be true? • I flows from a to b and is steady. • I flows from a to b and is decreasing. • I flows from b to a and is steady. • I flows from b to a and is increasing. • I flows from a to b and is increasing.

13. The potential at a is higher than the potential at b. Which of the following statements about the inductor current I could be true? • I flows from a to b and is steady. • I flows from a to b and is decreasing. • I flows from b to a and is steady. • I flows from b to a and is increasing. • I flows from a to b and is increasing.

14. What is the direction of the net force on the moving charge? • Into the page • Out of the page • Left • Right • Up and left at 45°

15. What is the direction of the net force on the moving charge? • Into the page • Out of the page • Left • Right • Up and left at 45°

16. Which diagram shows the fields in frame S´?

17. Which diagram shows the fields in frame S´?

18. The electric field in four identical capacitors is shown as a function of time. Rank in order, from largest to smallest, the magnetic field strength at the outer edge of the capacitor at time T. • Ba = Bb > Bc = Bd • Ba > Bb > Bc > Bd • Ba = Ba > Bc > Bd • Bc > Ba > Bd > Bb • Bd > Bc > Ba = Bb

19. The electric field in four identical capacitors is shown as a function of time. Rank in order, from largest to smallest, the magnetic field strength at the outer edge of the capacitor at time T. • Ba = Bb > Bc = Bd • Ba > Bb > Bc > Bd • Ba = Ba > Bc > Bd • Bc > Ba > Bd > Bb • Bd > Bc > Ba = Bb

20. An electromagnetic wave is propagating in the positive x-direction. At this instant of time, what is the direction of at the center of the rectangle? • In the positive x-direction • In the negative x-direction • In the positive y-direction • In the positive z-direction • In the negative z-direction

21. An electromagnetic wave is propagating in the positive x-direction. At this instant of time, what is the direction of at the center of the rectangle? • In the positive x-direction • In the negative x-direction • In the positive y-direction • In the positive z-direction • In the negative z-direction

22. An electromagnetic wave is traveling in the positive y-direction. The electric field at one instant of time is shown at one position. The magnetic field at this position points • In the positive x-direction. • In the negative x-direction. • In the positive y-direction. • In the negative y-direction. • Away from the origin.

23. An electromagnetic wave is traveling in the positive y-direction. The electric field at one instant of time is shown at one position. The magnetic field at this position points • In the positive x-direction. • In the negative x-direction. • In the positive y-direction. • In the negative y-direction. • Away from the origin.

24. Currents circulate in a piece of metal that is pulled through a magnetic field. What are these currents called? • Induced currents • Displacement currents • Faraday’s currents • Eddy currents • This topic is not covered in Chapter 33.

25. Currents circulate in a piece of metal that is pulled through a magnetic field. What are these currents called? • Induced currents • Displacement currents • Faraday’s currents • Eddy currents • This topic is not covered in Chapter 33.

26. Electromagnetic induction was discovered by • Faraday. • Henry. • Maxwell. • Both Faraday and Henry. • All three.

27. Electromagnetic induction was discovered by • Faraday. • Henry. • Maxwell. • Both Faraday and Henry. • All three.

28. The direction that an induced current flows in a circuit is given by • Faraday’s law. • Lenz’s law. • Henry’s law. • Hertz’s law. • Maxwell’s law.

29. The direction that an induced current flows in a circuit is given by • Faraday’s law. • Lenz’s law. • Henry’s law. • Hertz’s law. • Maxwell’s law.

30. The amplitude of the oscillating electric field at your cell phone is 4.0 µV/m when you are 10 km east of the broadcast antenna. What is the electric field amplitude when you are 20 km east of the antenna? • 1.0 µV/m • 2.0 µV/m • 4.0 µV/m • There’s not enough information to tell.

31. The amplitude of the oscillating electric field at your cell phone is 4.0 µV/m when you are 10 km east of the broadcast antenna. What is the electric field amplitude when you are 20 km east of the antenna? • 1.0 µV/m • 2.0 µV/m • 4.0 µV/m • There’s not enough information to tell.

32. Experimenter A creates a magnetic field in the laboratory. Experimenter B moves relative to A. Experimenter B sees • just the same magnetic field. • a magnetic field of different strength. • a magnetic field pointing the opposite direction. • just an electric field. • both a magnetic and an electric field.

33. Experimenter A creates a magnetic field in the laboratory. Experimenter B moves relative to A. Experimenter B sees • just the same magnetic field. • a magnetic field of different strength. • a magnetic field pointing the opposite direction. • just an electric field. • both a magnetic and an electric field.