POST-TEST

1. Teacher Phil asked his students to observe a circuit diagram illustrating the direction of electron flow from the negative to the positive terminal of a battery. He then instructed the students to hypothesize about the behavior of current flow in the circuit. Which of the following hypotheses best differentiates between conventional current and electron flow?

• a. Conventional current flows from the positive to the negative terminal, while electron flow moves from negative to positive.

• b. Conventional current flows from negative to positive, while electron flow moves from positive to negative.

• c. Conventional current and electron flow both moves from negative to positive.

• d. Conventional current flows in every direction.

2. 2. Imagine you’re trying to figure out how much charge passes through a wire. A current of 3A flows through it for 5 seconds. Based on the formula of electric charge, which of these ideas could you test?

• a. The charge passing through the wire will be less than 10 C.

• b. The charge doesn’t depend on the current or the time.

• c. The charge passing through the wire will be 15 C.

• d. The charge depends on the square of the current instead.

3. Imagine you’re conducting an experiment to see how a metallic conductor’s resistance changes when you increase the temperature. Which of these ideas best explains what will happen to the resistance as the temperature increases?

• a. The conductor’s resistance increases as the temperature increases.

• b. The conductor’s resistance decreases as the temperature increases.

• c. The temperature won’t affect the conductor’s resistance.

• d. After the temperature increases, the resistance will stay the same.

4. You are investigating the electrical conductivity of several materials. Which of the following hypotheses describing how a material's resistivity affects its ability to conduct electricity could be a valid hypothesis?

• a. High resistivity materials allow more current to flow through it.

• b. Materials with low resistance allows more current to flow.

• c. Current will flow through them all in the same way since every material has the same resistivity.

• d. High resistivity materials will conduct current in the same way as low resistivity materials.

5. You’re testing how the length of a wire affects its resistance. If you increase the length of the wire, what would you expect to happen to the resistance, based on the relationship between resistance and length?

• a. Regardless of the length, the resistance will stay the same.

• b. As the length of the wire increases, the resistance decreases

• c. The resistance decreases, then increases after a certain length.

• d. As the length of the wire increases, the resistance increases.

6. 6. The following I-V curves represent different materials. Based on the curves, which of the following hypotheses best explains the behavior of the materials shown in the graphs?

• a. Material A acts like a non-ohmic material, where its resistance changes as the voltage increases, while Material B acts like an ohmic material, where resistance stays the same.

• b. Material A acts like an ohmic material, where the current increases in a straight line with voltage, and Material B acts like a non-ohmic material, where resistance changes as voltage increases.

• c. Both Material A and Material B behave like ohmic materials, where the current increases in a steady, predictable way as voltage goes up.

• d. Both Material A and Material B behave like non-ohmic materials, where neither of their current-voltage relationships are straight lines.

7. Consider a basic circuit consisting of wires, a lightbulb, and a battery. The battery has a known emf (electromotive force), and you measure the potential difference (PD) across the light bulb. Which of the following hypotheses best describes the differences between the potential difference across the lightbulb and the emf of the battery?

• a. The PD across the lightbulb indicates how much energy is still in the circuit, whereas the emf of the battery represents the energy consumed by the circuit.

• b. Since the lightbulb consumes all of the battery's energy, the PD across it is always equal to the emf of the battery.

• c. The PD across the lightbulb is always greater than the emf of the battery due to energy lost in the wires.

• d. The PD across the lightbulb indicates how much energy the lightbulb consumes, whereas the battery's emf indicates how much energy the battery supplies to the circuit.

8. 8. In the circuit below, the student wants to calculate the power supplied by the battery and the power dissipated by the resistor. The student hypothesizes that these values are equal in an ideal circuit. Which of the following would be the most effective question to test this hypothesis?

• a. How can the emf of the battery and the resistance of the resistor be used to calculate the power dissipated and supplied?

• b. What happens to the power dissipated by the resistor if the resistance increases to 4Ω?

• c. Why does the power dissipated by the resistor depend only on its resistance and not the battery's emf?

• d. How does the relationship between current and resistance affect the power supplied by the battery?

9. Nicole plugs a 60W lightbulb into a 120V power source at home. She wants to find out how much current the bulb uses. What is the current drawn by the lightbulb?

• a. 0.25A

• b. 0.3A

• c. 0.5A

• d. 2.0A

10. Joan is troubleshooting a small lamp in her house. She connects the lamp to a 24V battery and measures a current of 2A flowing through it. She wants to find the resistance of the lamp to make sure it’s working properly. Using Ohm’s Law, what is the resistance of the lamp?

• a. 6Ω              

• b. 8Ω  

• c. 10Ω

• d. 12Ω