AP Physics 2 Flashcards: Resistance Resistivity And Ohms Law

What this deck covers

This deck focuses on Resistance Resistivity And Ohms Law, giving you a quick way to review the definitions, rules, and examples that matter most for AP Physics 2.

How to use these flashcards

Work through these flashcards in short sessions. Try to answer each prompt before flipping the card, then revisit any cards you miss until the explanation feels automatic.

Flashcard 1: What is the formula for power in terms of current and voltage?

Answer: $P = IV$. Power equals current times voltage.

Flashcard 2: How does increasing length of a wire affect resistance?

Answer: Increases resistance. Longer path means more resistance to current flow.

Flashcard 3: Find $R$ if $P = 100\text{W}$ and $I = 10\text{A}$.

Answer: $R = 1\text{Ω}$. Using $P = I^2R$, so $R = \frac{P}{I^2} = \frac{100}{100} = 1\text{Ω}$.

Flashcard 4: What is Ohm's Law formula?

Answer: $V = IR$. Relates voltage, current, and resistance linearly.

Flashcard 5: Calculate the current if $V = 12\text{V}$ and $R = 4\text{Ω}$.

Answer: $I = 3\text{A}$. Using $I = \frac{V}{R} = \frac{12}{4} = 3\text{A}$.

Flashcard 6: What does the variable $V$ represent in Ohm's Law?

Answer: Voltage. The electric potential difference across a component.

Flashcard 7: Calculate the power if $I = 5\text{A}$ and $V = 12\text{V}$.

Answer: $P = 60\text{W}$. Using $P = IV = 5 \times 12 = 60\text{W}$.

Flashcard 8: Find the resistivity if $R = 8\text{Ω}$, $L = 4\text{m}$, and $A = 2\text{m}^2$.

Answer: $\rho = 4\text{Ωm}$. Using $\rho = R \frac{A}{L} = 8 \times \frac{2}{4} = 4\text{Ωm}$.

Flashcard 9: What does an increase in cross-sectional area do to resistance?

Answer: Decreases resistance. Larger area provides more parallel paths for current.

Flashcard 10: Calculate resistance using resistivity $\rho = 1.68 \times 10^{-8}\text{Ωm}$, length $L = 2\text{m}$, and area $A = 1\text{m}^2$.

Answer: $R = 3.36 \times 10^{-8}\text{Ω}$. Using $R = \rho \frac{L}{A} = 1.68 \times 10^{-8} \times \frac{2}{1}$.

Flashcard 11: Identify the unit for electric current.

Answer: Ampere ($\text{A}$). Named after André-Marie Ampère.

Flashcard 12: State the formula for power in terms of voltage and resistance.

Answer: $P = \frac{V^2}{R}$. Alternative power formula using voltage and resistance.

Flashcard 13: Find $V$ if $I = 3\text{A}$ and $R = 2\text{Ω}$.

Answer: $V = 6\text{V}$. Using $V = IR = 3 \times 2 = 6\text{V}$.

Flashcard 14: How does resistivity change with temperature for metals?

Answer: Increases with temperature. Thermal energy increases atomic vibrations in metals.

Flashcard 15: How is resistivity different from resistance?

Answer: Resistivity is material property; resistance depends on dimensions. Resistivity is intrinsic; resistance includes geometry.

Flashcard 16: What does the variable $V$ represent in Ohm's Law?

Answer: Voltage. The electric potential difference across a component.

Flashcard 17: What does a negative temperature coefficient of resistance mean?

Answer: Resistance decreases with temperature. Negative coefficient means resistance drops as temperature rises.

Flashcard 18: What does the variable $R$ represent in Ohm's Law?

Answer: Resistance. The opposition to current flow in a circuit.

Flashcard 19: Find $I$ if $P = 150\text{W}$ and $V = 30\text{V}$.

Answer: $I = 5\text{A}$. Using $I = \frac{P}{V} = \frac{150}{30} = 5\text{A}$.

Flashcard 20: Find $I$ if $P = 150\text{W}$ and $V = 30\text{V}$.

Answer: $I = 5\text{A}$. Using $I = \frac{P}{V} = \frac{150}{30} = 5\text{A}$.

Flashcard 21: What is the relationship between resistance and resistivity?

Answer: $R = \rho \frac{L}{A}$. Resistance equals resistivity times length over area.

Flashcard 22: How does resistance vary with temperature for a semiconductor?

Answer: Decreases with temperature. Semiconductors have negative temperature coefficient.

Flashcard 23: What is the formula for power in terms of resistance and current?

Answer: $P = I^2R$. Alternative power formula using current and resistance.

Flashcard 24: Which material has typically lower resistivity, copper or rubber?

Answer: Copper. Copper is an excellent conductor with low resistivity.

Flashcard 25: How does increasing length of a wire affect resistance?

Answer: Increases resistance. Longer path means more resistance to current flow.

Flashcard 26: Calculate the resistance if $V = 10\text{V}$ and $I = 2\text{A}$.

Answer: $R = 5\text{Ω}$. Using $R = \frac{V}{I} = \frac{10}{2} = 5\text{Ω}$.

Flashcard 27: What is the unit of conductance?

Answer: Siemens ($\text{S}$). Named after Ernst Werner von Siemens.

Flashcard 28: What unit is used to measure resistance?

Answer: Ohms ($\text{Ω}$). Named after Georg Ohm, measures opposition to current.

Flashcard 29: What is Ohm's Law formula?

Answer: $V = IR$. Relates voltage, current, and resistance linearly.

Flashcard 30: Find $V$ if $I = 3\text{A}$ and $R = 2\text{Ω}$.

Answer: $V = 6\text{V}$. Using $V = IR = 3 \times 2 = 6\text{V}$.

Flashcard 31: What does the symbol $\text{Ω}$ represent?

Answer: Ohm, unit of resistance. Greek letter omega represents the ohm unit.

Flashcard 32: What does the symbol $\text{Ω}$ represent?

Answer: Ohm, unit of resistance. Greek letter omega represents the ohm unit.

Flashcard 33: State the formula for resistivity.

Answer: $\rho = R \frac{A}{L}$. Rearranged from $R = \rho \frac{L}{A}$.

Flashcard 34: State the formula for resistivity.

Answer: $\rho = R \frac{A}{L}$. Rearranged from $R = \rho \frac{L}{A}$.

Flashcard 35: What unit is used to measure resistance?

Answer: Ohms ($\text{Ω}$). Named after Georg Ohm, measures opposition to current.

Flashcard 36: Find $R$ if $P = 100\text{W}$ and $I = 10\text{A}$.

Answer: $R = 1 \, \Omega$. Using $P = I^2R$, so $R = \frac{P}{I^2} = \frac{100}{100} = 1 \, \Omega$.

Flashcard 37: Calculate the current if $V = 12\text{V}$ and $R = 4\text{Ω}$.

Answer: $I = 3\text{A}$. Using $I = \frac{V}{R} = \frac{12}{4} = 3\text{A}$.

Flashcard 38: What is the effect of doubling the cross-sectional area on resistance?

Answer: Resistance is halved. Larger area provides more paths for current flow.

Flashcard 39: What is the formula for power in terms of resistance and current?

Answer: $P = I^2R$. Alternative power formula using current and resistance.

Flashcard 40: What is the reciprocal of resistance called?

Answer: Conductance. Conductance $G = \frac{1}{R}$, measures ease of current flow.

Flashcard 41: What is the unit of conductance?

Answer: Siemens ($\text{S}$). Named after Ernst Werner von Siemens.

Flashcard 42: What is one factor that affects resistivity?

Answer: Material. Resistivity depends only on material composition.

Flashcard 43: What happens to resistance if temperature increases?

Answer: Resistance increases. Higher temperature increases atomic vibrations, impeding current.

Flashcard 44: What is the unit of power in electric circuits?

Answer: Watt ($\text{W}$). Named after James Watt, measures energy per time.

Flashcard 45: What does $I$ represent in Ohm's Law?

Answer: Current. The flow of electric charge through a conductor.

Flashcard 46: What is one factor that affects resistivity?

Answer: Material. Resistivity depends only on material composition.

Flashcard 47: What is the reciprocal of resistance called?

Answer: Conductance. Conductance $G = \frac{1}{R}$, measures ease of current flow.

Flashcard 48: What does $I$ represent in Ohm's Law?

Answer: Current. The flow of electric charge through a conductor.

Flashcard 49: What happens to resistance if temperature increases?

Answer: Resistance increases. Higher temperature increases atomic vibrations, impeding current.

Flashcard 50: How does material affect resistivity?

Answer: Different materials have different resistivities. Resistivity is an intrinsic material property.

Flashcard 51: What is the relationship between voltage and current if resistance is constant?

Answer: Directly proportional. From Ohm's Law, $V = IR$ with constant $R$.

Flashcard 52: What happens to current if voltage is doubled while resistance is constant?

Answer: Current doubles. From Ohm's Law, current is proportional to voltage.

Flashcard 53: What is the effect of doubling the cross-sectional area on resistance?

Answer: Resistance is halved. Larger area provides more paths for current flow.

Flashcard 54: How does resistivity change with temperature for metals?

Answer: Increases with temperature. Thermal energy increases atomic vibrations in metals.

Flashcard 55: State the formula for power in terms of voltage and resistance.

Answer: $P = \frac{V^2}{R}$. Alternative power formula using voltage and resistance.

Flashcard 56: What is the effect of resistance on current?

Answer: Resistance reduces current. Higher resistance opposes and limits current flow.