Resistance, Resistivity, and Ohm's Law - AP Physics C: Electricity and Magnetism
Card 1 of 30
How is resistance affected by increasing the cross-sectional area of a wire?
How is resistance affected by increasing the cross-sectional area of a wire?
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Resistance decreases. Larger area provides more paths for current flow.
Resistance decreases. Larger area provides more paths for current flow.
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What happens to resistance if the length of the wire is doubled?
What happens to resistance if the length of the wire is doubled?
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Resistance doubles. Resistance is directly proportional to length.
Resistance doubles. Resistance is directly proportional to length.
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What is the relationship between current and resistance in Ohm's Law?
What is the relationship between current and resistance in Ohm's Law?
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Current is inversely proportional to resistance. From $V = IR$, current decreases as resistance increases.
Current is inversely proportional to resistance. From $V = IR$, current decreases as resistance increases.
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State the formula for calculating current using Ohm's Law.
State the formula for calculating current using Ohm's Law.
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$I = \frac{V}{R}$. Rearranging Ohm's Law to solve for current.
$I = \frac{V}{R}$. Rearranging Ohm's Law to solve for current.
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Calculate the current when $V = 24 \text{V}$ and $R = 8 \text{Ω}$.
Calculate the current when $V = 24 \text{V}$ and $R = 8 \text{Ω}$.
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$I = 3 \text{A}$. Using $I = \frac{V}{R} = \frac{24}{8} = 3 \text{A}$.
$I = 3 \text{A}$. Using $I = \frac{V}{R} = \frac{24}{8} = 3 \text{A}$.
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For a fixed voltage, what happens to power if resistance increases?
For a fixed voltage, what happens to power if resistance increases?
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Power decreases. From $P = \frac{V^2}{R}$, power is inversely related to resistance.
Power decreases. From $P = \frac{V^2}{R}$, power is inversely related to resistance.
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What does the symbol $\rho$ represent in resistance calculations?
What does the symbol $\rho$ represent in resistance calculations?
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Resistivity. Greek letter rho denotes the material's intrinsic resistance property.
Resistivity. Greek letter rho denotes the material's intrinsic resistance property.
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Find the voltage if $I = 5 \text{A}$ and $R = 4 \text{Ω}$.
Find the voltage if $I = 5 \text{A}$ and $R = 4 \text{Ω}$.
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$V = 20 \text{V}$. Using $V = IR = 5 \times 4 = 20 \text{V}$.
$V = 20 \text{V}$. Using $V = IR = 5 \times 4 = 20 \text{V}$.
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What is the resistance if resistivity is $2 \text{Ω}\text{m}$, length is $4 \text{m}$, and area is $1 \text{m}^2$?
What is the resistance if resistivity is $2 \text{Ω}\text{m}$, length is $4 \text{m}$, and area is $1 \text{m}^2$?
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$R = 8 \text{Ω}$. Using $R = \frac{\rho L}{A} = \frac{2 \times 4}{1} = 8 \text{Ω}$.
$R = 8 \text{Ω}$. Using $R = \frac{\rho L}{A} = \frac{2 \times 4}{1} = 8 \text{Ω}$.
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State the relationship between voltage and current in Ohm's Law.
State the relationship between voltage and current in Ohm's Law.
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Voltage is directly proportional to current. At constant resistance, voltage and current increase together.
Voltage is directly proportional to current. At constant resistance, voltage and current increase together.
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What is the formula for voltage drop across a resistor?
What is the formula for voltage drop across a resistor?
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$V = IR$. The potential difference across any resistive element.
$V = IR$. The potential difference across any resistive element.
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What is the effect on resistance if the cross-sectional area is halved?
What is the effect on resistance if the cross-sectional area is halved?
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Resistance doubles. Resistance is inversely proportional to cross-sectional area.
Resistance doubles. Resistance is inversely proportional to cross-sectional area.
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What is the resistance if resistivity is $2 \text{Ω}\text{m}$, length is $4 \text{m}$, and area is $1 \text{m}^2$?
What is the resistance if resistivity is $2 \text{Ω}\text{m}$, length is $4 \text{m}$, and area is $1 \text{m}^2$?
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$R = 8 \text{Ω}$. Using $R = \frac{\rho L}{A} = \frac{2 \times 4}{1} = 8 \text{Ω}$.
$R = 8 \text{Ω}$. Using $R = \frac{\rho L}{A} = \frac{2 \times 4}{1} = 8 \text{Ω}$.
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What is the effect on resistance if the cross-sectional area is halved?
What is the effect on resistance if the cross-sectional area is halved?
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Resistance doubles. Resistance is inversely proportional to cross-sectional area.
Resistance doubles. Resistance is inversely proportional to cross-sectional area.
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Identify the unit of voltage.
Identify the unit of voltage.
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Volt ($\text{V}$). Named after Alessandro Volta, measures electrical potential difference.
Volt ($\text{V}$). Named after Alessandro Volta, measures electrical potential difference.
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Calculate the voltage if $I = 10 \text{A}$ and $R = 3 \text{Ω}$.
Calculate the voltage if $I = 10 \text{A}$ and $R = 3 \text{Ω}$.
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$V = 30 \text{V}$. Using $V = IR = 10 \times 3 = 30 \text{V}$.
$V = 30 \text{V}$. Using $V = IR = 10 \times 3 = 30 \text{V}$.
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What is the resistance when $V = 15 \text{V}$ and $I = 3 \text{A}$?
What is the resistance when $V = 15 \text{V}$ and $I = 3 \text{A}$?
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$R = 5 \text{Ω}$. Using $R = \frac{V}{I} = \frac{15}{3} = 5 \text{Ω}$.
$R = 5 \text{Ω}$. Using $R = \frac{V}{I} = \frac{15}{3} = 5 \text{Ω}$.
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What is the effect of temperature on resistivity in metals?
What is the effect of temperature on resistivity in metals?
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Resistivity increases. Thermal energy increases atomic vibrations in metallic conductors.
Resistivity increases. Thermal energy increases atomic vibrations in metallic conductors.
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What symbol is used to denote resistance?
What symbol is used to denote resistance?
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$R$. Standard symbol representing electrical resistance in circuits.
$R$. Standard symbol representing electrical resistance in circuits.
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What is the resistance of a wire if its length and area are doubled?
What is the resistance of a wire if its length and area are doubled?
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Resistance remains constant. Both length and area scale proportionally, canceling each other.
Resistance remains constant. Both length and area scale proportionally, canceling each other.
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What quantity does the symbol $V$ represent?
What quantity does the symbol $V$ represent?
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Voltage. Standard symbol for electrical potential difference or voltage.
Voltage. Standard symbol for electrical potential difference or voltage.
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How does resistivity change with temperature in semiconductors?
How does resistivity change with temperature in semiconductors?
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Resistivity decreases. Higher temperature increases carrier density in semiconductors.
Resistivity decreases. Higher temperature increases carrier density in semiconductors.
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What happens to the current if voltage is constant and resistance is tripled?
What happens to the current if voltage is constant and resistance is tripled?
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Current is reduced to one-third. Current is inversely proportional to resistance.
Current is reduced to one-third. Current is inversely proportional to resistance.
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How is resistance related to the dimensions of a material?
How is resistance related to the dimensions of a material?
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Resistance is proportional to length and inversely to area. From the resistance formula $R = \frac{\rho L}{A}$.
Resistance is proportional to length and inversely to area. From the resistance formula $R = \frac{\rho L}{A}$.
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Calculate the resistivity given $R = 10 \text{Ω}$, $L = 2 \text{m}$, $A = 0.5 \text{m}^2$.
Calculate the resistivity given $R = 10 \text{Ω}$, $L = 2 \text{m}$, $A = 0.5 \text{m}^2$.
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$\rho = 2.5 \text{Ω}\text{m}$. Using $\rho = \frac{RA}{L} = \frac{10 \times 0.5}{2} = 2.5 \text{Ω}\text{m}$.
$\rho = 2.5 \text{Ω}\text{m}$. Using $\rho = \frac{RA}{L} = \frac{10 \times 0.5}{2} = 2.5 \text{Ω}\text{m}$.
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State the formula for Ohm's Law.
State the formula for Ohm's Law.
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$V = IR$. The fundamental relationship between voltage, current, and resistance.
$V = IR$. The fundamental relationship between voltage, current, and resistance.
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What is the unit of electrical resistance?
What is the unit of electrical resistance?
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Ohm ($\text{Ω}$). Named after Georg Ohm, the physicist who discovered Ohm's Law.
Ohm ($\text{Ω}$). Named after Georg Ohm, the physicist who discovered Ohm's Law.
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Define electrical resistivity.
Define electrical resistivity.
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Resistivity is a material property indicating how strongly it opposes current flow. An intrinsic property that varies by material composition and structure.
Resistivity is a material property indicating how strongly it opposes current flow. An intrinsic property that varies by material composition and structure.
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What is the formula for resistance in terms of resistivity?
What is the formula for resistance in terms of resistivity?
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$R = \frac{\rho L}{A}$. Shows resistance depends on material properties and geometry.
$R = \frac{\rho L}{A}$. Shows resistance depends on material properties and geometry.
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Define the term 'Ohm's Law'.
Define the term 'Ohm's Law'.
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The relationship $V = IR$ describes the proportionality of voltage, current, and resistance. The fundamental principle governing linear electrical circuits.
The relationship $V = IR$ describes the proportionality of voltage, current, and resistance. The fundamental principle governing linear electrical circuits.
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