11.3 Resistance, Resistivity, and Ohm's Law

• If voltage and current are given, Ohm's Law can be used to solve for resistance
• In a series circuit, the total resistance is the sum of the individual resistor values.


  True
• What does the temperature coefficient of resistance ($\alpha$) represent?


  Change in resistance per degree
• Resistance is the opposition to electric current flow
• What is the unit of resistivity?

  Ohm-meters
• Arrange the factors affecting resistance in the correct order:

  1️⃣ Resistivity

  2️⃣ Length

  3️⃣ Cross-sectional area
• What is the relationship between current and voltage in a resistor according to Ohm's Law?

  Directly proportional
• Match the variable with its correct unit:

  Resistance ↔️ Ohms

  Resistivity ↔️ Ohm-meters

  Length ↔️ Meters

  Cross-sectional Area ↔️ Square meters
• The relationship between voltage, current, and resistance is described by Ohm's Law.
• Resistivity is a material-specific value that measures how strongly a material opposes the passage of electrons.
• Resistance is inversely proportional to the cross-sectional area of a material.
• Match the concept with its correct unit:

  Resistance ↔️ Ohms

  Resistivity ↔️ Ohm-meters

  Voltage ↔️ Volts

  Current ↔️ Amperes
• The measure of opposition to electric current flow is called resistance
• Current is measured in amperes
• What is the unit of resistivity?

  Ohm-meters
• Resistance is measured in ohms
• The resistance of a copper wire with a resistivity of $1.68 \times 10^{ - 8} \Omega\cdot\text{m}$, a length of 2 meters, and a cross-sectional area of $4 \times 10^{ - 6} \text{m}^{2}$ is 0.0084
• If a resistor has a resistance of 10 Ω and a current of 2 A is flowing through it, what is the voltage drop across the resistor?

  20 V
• State Ohm's Law mathematically.

  $V =$$IR$
• Ohm's Law can be mathematically expressed as $V =$$IR$.


  True
• Resistance is directly proportional to the length of a conductor.

  True
• Resistance is measured in ohms
• Steps to apply Ohm's Law to solve circuit problems:

  1️⃣ Identify the given values

  2️⃣ Apply the formula $V =$$IR$

  3️⃣ Solve for the unknown variable
• Resistivity is an intrinsic property of a material that determines its resistance.


  True
• Unlike resistance, resistivity is independent of the shape and size
• Resistance increases with the cross-sectional area of a material.

  False
• Ohm's Law can be used to solve for unknown quantities in electric circuits if two of the three variables are known.


  True
• What is the resistance of a copper wire with a resistivity of $1.68 \times 10^{ - 8} \Omega\cdot\text{m}$, a length of 2 meters, and a cross-sectional area of $4 \times 10^{ - 6} \text{m}^{2}$?


  0.0084 ohms
• What is the definition of resistivity?

  Intrinsic resistance property
• What is the formula for Ohm's Law?

  $V =$$IR$
• What is the resistance of a copper wire with a resistivity of $1.68 \times 10^{ - 8} \Omega\cdot\text{m}$, a length of 2 meters, and a cross-sectional area of $4 \times 10^{ - 6} \text{m}^{2}$?


  0.0084 ohms
• What is the unit of resistance?

  Ohms
• What is the unit of resistivity?

  Ohm-meters
• What is the measure of the potential difference that drives electric current?

  Voltage
• Voltage is measured in volts.

  True
• What is the unit of voltage?

  Volts
• What is the formula for Ohm's Law?

  $V =$$IR$
• Resistance is a measure of the opposition to the flow of electric current
• What is the difference between resistance and resistivity in terms of dependency on material dimensions?

  Resistivity is independent
• What does Ohm's Law describe for a given resistance in a circuit?

  Current is proportional to voltage