2.1.3 Resistance

• What is resistance a measure of in a circuit?

  Opposition to current flow
• Resistance is defined as the ratio of potential difference to current.
• If a circuit has a potential difference of 12V and a current of 2A, what is the resistance?

  6Ω
• What does Ohm's Law state about the relationship between current, voltage, and resistance?

  V = IR
• According to Ohm's Law, as voltage increases, current increases.
• Inversely proportional relationships mean that as one quantity increases, the other decreases.
• What is the formula to calculate resistance using Ohm's Law?

  $R =$$\frac{V}{I}$
• If a circuit has a voltage of 24V and a current of 4A, what is the resistance?

  6Ω
• Ohm's Law states that current is directly proportional to voltage.
• According to Ohm's Law, as voltage increases, current also increases.
• If a circuit has a voltage of 12V and a resistance of 4Ω, what is the current?

  3A
• Match the term with its symbol and unit:

  Voltage ↔️ V ||| Volts

  Current ↔️ I ||| Amperes

  Resistance ↔️ R ||| Ohms
• What happens to the current in a circuit as voltage increases?

  Current increases
• As resistance increases, current decreases in a circuit.
• In Ohm's Law, the voltage is measured in volts
• What is the relationship between voltage and current in Ohm's Law?

  Directly proportional
• What is the unit of current in Ohm's Law?

  Amperes
• Ohm's Law states that current is directly proportional to voltage and inversely proportional to resistance.
• What does the symbol $R$ represent in Ohm's Law?


  Resistance
• The unit of resistance in Ohm's Law is ohms
• What is the formula to calculate resistance using Ohm's Law?

  $R =$$\frac{V}{I}$
• If a circuit has a voltage of 24V and a current of 4A, what is the resistance?

  $6\Omega$
• Resistance is the ratio of voltage to current in a conductor.
• Longer conductors have greater resistance
• What happens to resistance when the cross-sectional area of a conductor increases?

  Resistance decreases
• Higher temperature increases the resistance of a conductor.
• What is the formula for calculating total resistance in a series circuit?

  R_{total} = R_{1} + R_{2} + ...</latex>
• What is the formula for calculating total resistance in a parallel circuit?

  $\frac{1}{R_{total}} =$$\frac{1}{R_{1}} +$$\frac{1}{R_{2}} +$$...$
• In a series circuit, resistors are connected along a single path
• How is total resistance calculated in a parallel circuit if $R_{1} =$$5\Omega$, $R_{2} =$$10\Omega$, and $R_{3} =$$15\Omega$?


  $R_{total} \approx 2.73\Omega$