1. © 2013 Pearson Education, Inc. Does the bulb light? A.Yes. B.No. C.I’m not sure. https://www.youtube.com/watch?v=aIhk9eKOLz Q

2. © 2013 Pearson Education, Inc. Every minute, 120 C of charge flow through this cross section of the wire. The wire’s current is A. 240 A. B. 120 A. C. 60 A. D. 2 A. E. Some other value.

3. © 2013 Pearson Education, Inc. The current density in this wire is A. 4  10 6 A/m 2. B. 2  10 6 A/m 2. C. 4  10 3 A/m 2. D. 2  10 3 A/m 2. E. Some other value.

4. © 2013 Pearson Education, Inc. Surface charge is distributed on a wire as shown. Electrons in the wire A. Drift to the right. B. Drift to the left. C. Move upward. D. Move downward. E. On average, remain at rest.

5. © 2013 Pearson Education, Inc. The current in the fourth wire is A. 16 A to the right. B. 4 A to the left. C. 2 A to the right. D. 2 A to the left. E. Not enough information to tell.

6. © 2013 Pearson Education, Inc. A piece of copper wire is stretched until it is twice as long. The ratio of the new resistance to old resistance is then A. 1/4. B. 1/2. C. 1. D. 2. E. 4.

7. © 2013 Pearson Education, Inc. Both segments of the wire are made of the same metal. Current I 1 flows into segment 1 from the left. How does current I 1 in segment 1 compare to current I 2 in segment 2 ? A. I 1 > I 2. B. I 1 = I 2. C. I 1 < I 2. D. There’s not enough information to compare them.

8. © 2013 Pearson Education, Inc. Both segments of the wire are made of the same metal. Current I 1 flows into segment 1 from the left. How does current density J 1 in segment 1 compare to current density J 2 in segment 2 ? A. J 1  J 2. B. J 1  J 2. C. J 1  J 2. D. There’s not enough information to compare them.

9. © 2013 Pearson Education, Inc. Both segments of the wire are made of the same metal. Current I 1 flows into segment 1 from the left. How does the electric field E 1 in segment 1 compare to the electric field E 2 in segment 2 ? A. E 1 > E 2. B. E 1 = E 2 but not zero. C. E 1 < E 2. D. Both are zero because metal is a conductor. E. There’s not enough information to compare them.

10. © 2013 Pearson Education, Inc.

11. A and B are identical lightbulbs connected to a battery as shown. Which is brighter? A. Bulb A. B. Bulb B. C. The bulbs are equally bright. http://phet.colorado.edu/en/simulation/battery-resistor- circuit

12. © 2013 Pearson Education, Inc. The current through a wire is measured as the potential difference  V is varied. What is the wire’s resistance? 0.01 . 0.02 . 50 . 100 . Some other value.

13. © 2013 Pearson Education, Inc. Draw circuit diagram

14. © 2013 Pearson Education, Inc.

15. Summary:

16. © 2013 Pearson Education, Inc. Courtesy of http://xkcd.com Midterm exam question: