This question tests understanding of resistance, resistivity, and Ohm's Law in AP Physics C: Electricity and Magnetism. From Ohm's Law V = IR, rearranged as I = V/R, we see that current is inversely proportional to resistance when voltage is constant. In the device circuit described, decreasing resistance R while maintaining fixed voltage V causes current I to increase, following the inverse relationship in the equation. Choice B is correct because decreasing R increases I at fixed V, as shown mathematically by I = V/R - when the denominator decreases, the quotient increases. Choice A is incorrect because it suggests current decreases when resistance decreases, which contradicts both Ohm's Law and physical intuition about reduced opposition to flow. Students should think of this like water flow: reducing resistance is like widening a pipe, allowing more current to flow at the same pressure (voltage). Practice with reciprocal relationships helps build intuition for inverse proportionality.

This question tests understanding of resistance, resistivity, and Ohm's Law in AP Physics C: Electricity and Magnetism. The passage explains that household circuits use low-resistivity (low-ρ) materials as conductors to carry current efficiently and high-resistivity (high-ρ) materials as insulators for safety. Glass is an insulator with very high resistivity (typically $10^12$ to $10^16$ Ω·m), while copper is an excellent conductor with very low resistivity (about 10^-8 Ω·m). Choice A is correct because glass, being an insulator, has resistivity many orders of magnitude higher than copper, which is why glass can be used as an electrical insulator. Choice B is incorrect as it reverses this fundamental property - copper's extremely low resistivity is precisely why it's the standard material for electrical wiring. Students should understand that the resistivity difference between insulators and conductors is enormous, often exceeding 20 orders of magnitude. This vast difference enables the safe design of electrical systems where current flows through copper wires but not through glass or ceramic insulators.

This question tests understanding of resistance, resistivity, and Ohm's Law in AP Physics C: Electricity and Magnetism. According to Ohm's Law V = IR, rearranged as I = V/R, current is directly proportional to voltage when resistance remains constant. In the household circuit with a fixed-resistance filament, doubling the voltage while keeping resistance unchanged must double the current to satisfy Ohm's Law. Choice A is correct because it accurately describes this direct proportional relationship: when V doubles at fixed R, I must also double according to I = V/R. Choice B is incorrect as it suggests an inverse relationship between voltage and current, which contradicts Ohm's Law when resistance is constant. Students should recognize that Ohm's Law describes a linear relationship - graphing I vs V at constant R yields a straight line through the origin with slope 1/R. Numerical practice helps: if R = 10Ω and V increases from 20V to 40V, current increases from 2A to 4A.

This question tests understanding of resistance, resistivity, and Ohm's Law in AP Physics C: Electricity and Magnetism. Resistivity (ρ) is a fundamental material property measured in Ω·m that indicates how strongly a material opposes electric current flow, with conductors having low resistivity and insulators having high resistivity. The passage indicates that household wiring uses conductors (like copper) with low resistivity for carrying current and insulators (like plastic) with high resistivity for safety. Choice B is correct because plastic, being an insulator, has much higher resistivity than copper, which is an excellent conductor with very low resistivity. Choice A is incorrect because it reverses the relationship - copper's low resistivity is precisely why it's used for electrical wiring. Students should memorize typical resistivity values: copper (~10^-8 Ω·m) versus plastic insulators $(~10^12$ to $10^16$ Ω·m). Understanding the vast difference in resistivity between conductors and insulators helps explain why current flows through wires but not through their plastic coatings.

This question tests understanding of resistance, resistivity, and Ohm's Law in AP Physics C: Electricity and Magnetism. Ohm's Law (V = IR) establishes that for a fixed voltage, current and resistance are inversely related, meaning I = V/R. In the lightbulb filament example, when resistance R increases while voltage remains constant, the current I must decrease to maintain the equality in Ohm's Law. Choice A is correct because it accurately describes the inverse relationship: increasing R decreases I when V is fixed, as shown by the equation I = V/R. Choice B is incorrect because it suggests current increases with resistance, which would violate Ohm's Law and energy conservation principles. Students should think of resistance as opposition to current flow - more opposition means less current, like a narrower pipe reducing water flow. Practice with numerical examples helps: if V = 12V and R increases from 4Ω to 6Ω, current decreases from 3A to 2A.

This question tests understanding of resistance, resistivity, and Ohm's Law in AP Physics C: Electricity and Magnetism. Ohm's Law V = IR can be rearranged to I = V/R, clearly showing that current equals voltage divided by resistance. In the household device example, when resistance increases while voltage stays constant, the current must decrease according to this inverse relationship shown in the equation I = V/R. Choice B is correct because it both states the correct outcome (current decreases) and provides the correct mathematical relationship (I = V/R) that explains why this happens. Choice A is incorrect because it presents a mathematically impossible equation I = VR, which would have incorrect units and suggest current increases with resistance. Students should always check their equation rearrangements using dimensional analysis: I[A] = V[V]/R[Ω] gives correct units, while I = VR would give units of V·Ω, not amperes. Understanding the mathematical form reinforces the conceptual inverse relationship.

This question tests understanding of resistance, resistivity, and Ohm's Law in AP Physics C: Electricity and Magnetism. Ohm's Law V = IR shows that for constant voltage, current and resistance have an inverse relationship, expressed as I = V/R. In the lightbulb circuit example, when the filament's resistance increases while the applied voltage remains constant, the current through the bulb must decrease to satisfy Ohm's Law. Choice B is correct because it accurately states that current decreases as resistance increases when voltage is constant, following directly from the mathematical relationship I = V/R. Choice A is incorrect as it suggests a direct relationship between current and resistance, which would violate Ohm's Law and conservation principles. Students should understand that increased resistance means more opposition to current flow, like a dimmer switch increasing resistance to reduce bulb brightness. Practice with real circuits helps: a 60W bulb has lower resistance than a 40W bulb, so it draws more current at the same voltage.

This question tests understanding of resistance, resistivity, and Ohm's Law in AP Physics C: Electricity and Magnetism. Ohm's Law states that V = IR, which can be rearranged to I = V/R, showing that current is inversely proportional to resistance when voltage is constant. In the household circuit example, when a lightbulb's resistance increases while voltage remains fixed, the current must decrease according to this inverse relationship. Choice A is correct because it accurately reflects that current decreases as resistance increases when voltage is constant, following directly from I = V/R. Choice B is incorrect because it suggests a direct proportional relationship between current and resistance, which contradicts Ohm's Law. Students should practice rearranging Ohm's Law to solve for different variables and understand the inverse relationship between current and resistance. Using dimensional analysis can help verify that the units work out correctly: V (volts) = A (amperes) × Ω (ohms).

This question tests understanding of resistance, resistivity, and Ohm's Law in AP Physics C: Electricity and Magnetism. Resistivity (ρ) is an intrinsic material property measured in Ω·m that quantifies how strongly a material opposes current flow, independent of the material's shape or size. The passage emphasizes that materials are chosen for circuits based on their resistivity: conductors like copper have very low resistivity while insulators like rubber have very high resistivity. Choice B is correct because rubber, as an insulator, has resistivity many orders of magnitude higher than copper (rubber $~10^13$ Ω·m vs copper ~10^-8 Ω·m). Choice A is incorrect because it reverses this fundamental relationship - copper's low resistivity makes it ideal for conducting electricity. Students should understand that resistivity differences between conductors and insulators can span over 20 orders of magnitude. This enormous difference explains why rubber can safely insulate copper wires carrying dangerous currents.

This question tests understanding of resistance, resistivity, and Ohm's Law in AP Physics C: Electricity and Magnetism. Ohm's Law (V = IR) can be rearranged to I = V/R, showing that current is directly proportional to voltage when resistance is constant. In the lamp circuit described, if voltage doubles while resistance stays the same, the current must also double to maintain the equality in Ohm's Law. Choice A is correct because when V doubles and R remains constant, I must double according to I = V/R, demonstrating the direct proportional relationship. Choice B is incorrect because it suggests an inverse relationship between voltage and current, which contradicts Ohm's Law when resistance is fixed. Students should visualize this relationship using graphs of I vs V at constant R, which produce straight lines through the origin. Practice problems involving proportional reasoning help reinforce that doubling the cause (voltage) doubles the effect (current) in linear relationships.