Review: Unit 1
The 63 minute video below gives an overview of what to expect on the Unit 1 Test along with many example problems. Additionally, the learner objectives for this unit, given by the College Board, are listed and explained. Knowing these objectives provides a very real advantage to the student on the AP* exam, because the questions on the exam are all related to the learner objectives. Additionally, you should attempt the additional practice problems shown below the video.
Practice Problems
Click here to see the answers to the problems.
1. Write a rebuttal to the false claim shown below.
"A student uses a voltmeter to measure the electric potential at various positions on the surface of an irregularly-shaped charged hunk of metal. She gets readings that are high in some locations and low in other locations."
Please write your rebutal with formatting that highlights the claim in yellow, the evidence in green, and the justification in blue. Recall that evidence is something you can observe or measure, while justification is the conceptual rationale for why the evidence is supportive of the claim.
2. Two identical 5Ω resistors and a 10Ω resistor are connected in a circuit. Which of the following cannot be the effective resistance of these resistors?
- 20 Ω
- 12.5 Ω
- 8.3 Ω
- 17.5 Ω
3. Three identical resistors (R) are connected in a circuit so that two are in series and the third is in parallel with the combination of the first two. If connected to a battery individually, each resistor dissipates power P. Determine the power dissipated by the network combination when connected to the same source.
4. A 10 volt ideal battery is in a circuit with three light bulbs, each with 2Ω of resistance, and a fuse. The fuse has extremely low resistance in comparison to the bulbs and is rated to melt at 2A. If all the elements in the circuit are in series with each other, connected with ideal wires, will the fuse melt when the circuit is connected?
5. Consider the following circuits:
Circuit 1: A 10 v battery in series with two 10 Ω resistors
Circuit 2: Two 10 v batteries in series with three 10 Ω resistors
Circuit 3: Three 10 v batteries in series with two 10 Ω resistors
Circuit 4: A 10 v battery connected to two 10 Ω resistors that are in parallel
Circuit 5: Two 10 v batteries in parallel with each other in series with two 10 Ω resistors
Which of the circuits above would have the same current through each resistor as the current in a circuit containing a single 10 v battery and a 10 Ω resistor?
- Circuit 1
- Circuit 2
- Circuit 3
- Circuit 4
- Circuit 5
6. Two 20 v batteries are in series, connected positive pole to negative pole. They each have internal resistance of 5 Ω. What power is dissipated in one of the batteries?
7. Two point charges are brought closer together, increasing the force between them by a factor of 100. By what factor was their separation decreased?
8. Point charges of 1.00µC and –1.00µC make up an electric dipole along the x-axis. Can a third charge be placed on the x-axis so that the net force on it is zero? What if both charges are positive?
9. A. Sketch the electric field lines near a point charge +q.
B. Do the same for a point charge –3.00q.
10. If the electric potential due to a point charge is 200 V at a distance of 10.0 m, what are the sign and magnitude of the charge?
11. What is the potential difference between two points situated 30 cm and 40 cm from a 2.0 µC point charge? To what location should the point at 30 cm be moved to increase this potential difference by a factor of three?
12. Sketch the equipotential lines for the two equal positive charges shown below. Indicate the direction of increasing potential.
13. Use Kirchhoff's Rules to analyze the circuit below.
a. Write a point rule for point C.
b. Write a loop rule for each loop shown.
c. Determine the three unknowns (I1, I2, and ε).
d. Determine the % increase in power dissipated by the internal resistance of the unknown battery if that battery was short-circuited.
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