Physics 2 · Unit 3 · Paper 3

Electric Circuits unit test

A test on this unit alone, marked as a percentage and a letter grade — for the test your class is actually sitting, rather than for May. Answer everything, then submit once: seeing the answer to question 3 before attempting question 4 makes the final percentage meaningless.

Paper 1 Paper 2 Paper 3

Each paper is built from this unit’s 47 terms and is the same for everyone, so a teacher can assign “Unit 3, Paper 3” and every student sits the identical test. Multiple choice is marked objectively; the written sections you mark yourself against the model answer and rubric.

Suggested time 35 min 32 points0/17 attempted

Current

Series resistors

Resistance and resistivity

Ideal voltmeter

Effect of adding a parallel branch

Capacitance

Kirchhoff sign conventions

Series vs parallel capacitor voltage

Capacitor charging graph

Three forms of power

Meters connected wrongly

Choosing the power form

Short answer 1. Define or explain: emf versus terminal voltage

3 pts

Short answer 2. Define or explain: RC time constant

3 pts

Short answer 3. Define or explain: Conventional current direction

3 pts

Short answer 4. Define or explain: Brightness reasoning

3 pts

Free response

8 pts

A battery of emf 18.0 V and internal resistance 1.0 Ω is connected to a 5.0 Ω resistor in series with a parallel combination of a 12 Ω resistor and a 6.0 Ω resistor. (a) Calculate the equivalent resistance of the external circuit and the current delivered by the battery. Show your work. (b) Calculate the terminal voltage of the battery and the power dissipated inside the battery. (c) Calculate the current through the 12 Ω resistor and the power it dissipates. (d) The 6.0 Ω resistor burns out and becomes an open circuit. State and justify whether the power dissipated in the 5.0 Ω resistor increases, decreases or stays the same. Support your answer with a calculation.

Calculate the external equivalent resistance and the battery current.

Calculate the terminal voltage and the power dissipated internally.

Calculate the current through and power dissipated in the 12 Ω resistor.

Determine and justify the change in power in the 5.0 Ω resistor when the 6.0 Ω opens.