Reading:

Cutnell and Johnson, Section 19.5; Chapter 20 excluding sections 20.3, 20.5, 20.13.

Problems for Review:

Reviewing these problems gives you good exposure to this week's main topics, in practice. All are worked in the Student Study Guide [SSG] or Student Solutions Manual [SSM]; solutions are posted on our website http://www.physics.emory.edu/Classes/142-003.html , for those without these texts.

Conceptual:

MCAT review problem, [SSG] p 397.

Quantitative:

Chapter 19, problems 45, 57 (from last homework) Chapter 20, problems 25, 41, 45, 53, 57, 61, 65, 73, 77, 81, 93.

Problems to Hand In:

Conceptual:

Use the following to answer questions 1--7:

The following circuit contains one voltage source (a battery with 27 V emf), as well as several resistors, some wired in parallel and some in series:

1. This question compares the current through the 0.5 and 7 resistors. The current through the 7 resistor is
   1. equal to
   2. slightly less than
   3. 14 times
   4. (1/14) times
   the current through the 0.5 resistor.
2. This question compares the voltage (or potential drop) across the 0.5 and 7 resistors. The voltage across the 7 resistor is
   1. equal to
   2. slightly less than
   3. 14 times
   4. (1/14) times
   the voltage across the 0.5 resistor.
3. Complete the following: the current through the 2 resistor is
   1. less than the current through the 7 resistor, but equal to the current through the 6 resistor.
   2. less than the current through the 7 resistor, but 3 times the current through the 6 resistor.
   3. less than the current through the 7 resistor, and one third of the current through the 6 resistor.
   4. equal to the current through the 7 resistor.
4. The equivalent resistance of the 6 and 2 resistors is
   1. 1/8
   2. 2
   3. 3/2
   4. 3
5. Consider adding a third resistor wired in parallel between points A and B. The equivalent resistance between A and B
   1. would increase.
   2. would decrease.
   3. would remain the same.
   4. could increase or decrease, depending on the resistor added.

   
   

   For questions 6 and 7, consider connecting points A and B by a resistance-less wire in parallel to the 6 and 2 resistors, ``shorting'' the resistors.

   
   

6. After the wire is added, the current through the 6 resistor
   1. decreases to nothing.
   2. decreases slightly.
   3. stays the same.
   4. increases.
7. After the wire is added, the current through the 7 resistor
   1. decreases to nothing.
   2. decreases slightly.
   3. stays the same.
   4. increases.

Quantitative:

Chapter 19, problems 46, 62.
Chapter 20, problems 44, 56, 60, 72, 78, 80, 86, 90.

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