AP Physics C Exam Questions on Power Dissipation in Resistors

⚡ Quick Study Guide

• 💡 Power Dissipation: Resistors convert electrical energy into heat. The power dissipated ($P$) is given by several formulas:
• 🔥 $P = IV$, where $I$ is current and $V$ is voltage.
• 📏 $P = I^2R$, where $I$ is current and $R$ is resistance.
• 📐 $P = \frac{V^2}{R}$, where $V$ is voltage and $R$ is resistance.
• ➕ Ohm's Law: $V = IR$. This relates voltage, current, and resistance.
• ⏱️ Units: Power is measured in watts (W). 1 W = 1 J/s.

✍️ Practice Quiz

1. A resistor with a resistance of 10 $\Omega$ has a current of 2 A flowing through it. What is the power dissipated by the resistor?
   1. 4 W
   2. 20 W
   3. 40 W
   4. 80 W
2. A 12 V battery is connected to a 4 $\Omega$ resistor. What is the power dissipated by the resistor?
   1. 3 W
   2. 12 W
   3. 36 W
   4. 48 W
3. If the current through a 5 $\Omega$ resistor is doubled, by what factor does the power dissipated increase?
   1. 1
   2. 2
   3. 4
   4. 8
4. A resistor dissipates 20 W of power when connected to a 10 V source. What is the resistance of the resistor?
   1. 2 $\Omega$
   2. 5 $\Omega$
   3. 10 $\Omega$
   4. 20 $\Omega$
5. Two resistors, 𝑅₁ = 2 $\Omega$ and 𝑅₂ = 4 $\Omega$, are connected in series to a 12 V source. What is the power dissipated by 𝑅₂?
   1. 8 W
   2. 16 W
   3. 32 W
   4. 64 W
6. Two resistors, 𝑅₁ = 6 $\Omega$ and 𝑅₂ = 3 $\Omega$, are connected in parallel to a 9 V source. What is the total power dissipated by the circuit?
   1. 27 W
   2. 40.5 W
   3. 12 W
   4. 15 W
7. A variable resistor is connected to a constant voltage source. As the resistance increases, what happens to the power dissipated?
   1. Increases
   2. Decreases
   3. Remains the same
   4. Increases then decreases