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AP PHYSICS 2
Circuits 1 Problem Set
1. Explain why birds can sit on powerlines safely, even though the wires have no insulation
around them, whereas leaning a metal ladder up against a powerline is extremely dangerous.
(Giancoli, 19-Q1)
2. Discuss the advantages and disadvantages of Christmas tree lights connected in parallel
versus those connected in series. (Giancoli, 19-Q2)
3. With two identical lightbulbs and two identical batteries, explain how and why you would
arranged the bulbs and batteries in a circuit to get the maximum possible total power to the
light bulbs. (Ignore batteries’ internal resistance.) (Giancoli, 19-Q6)
4. You have a single 60-W bulb lit in your room. How does the overall resistance of your
room’s electrical circuit change when you turn on an additional 100-W bulb? Explain.
(Giancoli, 19-Q8)
5. Different lamps might have batteries connected in either of
the two arrangements as shown at the right. What are the
advantages of each scheme? (Giancoli, 19-Q11)
6. Two identical 10-V batteries and two identical 10- resistors
are placed in series as shown. If a lightbulb with a 10 
resistance is connected with one end between the batteries and
the other end between the resistors, how much current will
flow through the bulb? (Giancoli, 19-MQ4)
7. Which resistor has the greatest current going
through it? Assume that all the resistors have
equal resistance. (Giancoli, 19-MQ5)
8. Rank the brightness of the identical bulbs. Briefly explain your
reasoning. (Etkina, review 16.29)
AP Physics 2
Circuits 1 Problem Set
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Use the diagram at right to answer questions 9-10.
9. When the switch is closed, what will happen to the voltage
across resistor 1? Will it increase, decrease, or stay the same?
Briefly explain. (Giancoli, 19-MQ7)
10. When the switch is closed, what will happen to voltage across
resistor 4? Will it increase, decrease, or stay the same? Briefly
explain. (Giancoli, 19-MQ8)
11. Most cars have 12.0-V batteries. (Giancoli, 19-3)
a. What is the internal resistance of a 12.0V car battery whose terminal voltage drops
to 8.8 V when the start motor draws 95 A?
b. What is the resistance of the starter motor?
AP Physics 2
Circuits 1 Problem Set
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12. Read Example 19-9 in Giancoli (pp. 536-7). If the jumper cables
were mistakenly (!!) connected from the positive terminal of
the good battery with negative terminal of the dead battery,
a. what would the current be even before the switch (to
starter motor) is closed? (Resistance in jumper cables is
0.0026 )
b. How much power is dissipated by dead battery? Why might this cause the
battery to explode?
13. A 650- resistor and an 1800- resistor are connected in series with a 12-V battery.
What is the voltage across the 1800- resistor? (Giancoli, 19-4)
14. How many 10- resistors must be connected in series to give an equivalent resistance to
five 100- resistors connected in parallel? (Giancoli, 19-7)
AP Physics 2
Circuits 1 Problem Set
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15. A 1380-W electric heater, a 180-W computer, a 120-W
lightbulb, and a 1200-W microwave are plugged into the
same wall sockets in the same part of the house. When
the current through the main line exceeds 20 A, a circuit
breaker opens the circuit. Will the circuit breaker open
the circuit if all these appliances are in operation at the
same time? (Etkina, Exercise 16.12)
Use the scenario below to answer questions 16-18.
Some students are given a voltmeter and a resistor with an unknown resistance. (AP Test)
16. Briefly describe a procedure students could follow to determine if the resistor is ohmic.
Assume you have additional known resistors, a variable voltage source, and an ammeter.
17. Using standard symbols for circuit elements, draw a diagram of a circuit that the students
could use to determine whether the resistor X is ohmic. Include appropriate placement of
meters (i.e., in series or in parallel). Include clear labels.
AP Physics 2
Circuits 1 Problem Set
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18. What would you graph using your data? What would you look for in your graph to
determine whether resistor X is ohmic?
19. A group of students wants to determine the internal resistance of a battery. They connect
the battery to a variable resistor. The students then measure the potential difference
across the battery as a function of current through the battery as they vary the resistance.
(AP Test)
a. What data do you recommend they graph?
b. What value from the graph yields internal resistance of the battery? Briefly
explain.
AP Physics 2
Circuits 1 Problem Set
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