Internal Resistance Quiz: Test Your Understanding

📚 Quick Study Guide

• 🔋 Internal Resistance (r): The resistance within a voltage source (like a battery) that reduces the actual voltage delivered to a circuit.
• 📏 Ohm's Law: $V = IR$, where V is voltage, I is current, and R is resistance.
• ⚡️ Terminal Voltage (V_T): The actual voltage output of a voltage source, which is less than the EMF (electromotive force, ε) due to internal resistance: $V_T = \varepsilon - Ir$.
• 💡 EMF (ε): The electromotive force, representing the total voltage provided by the source when no current is flowing.
• 🔥 Power Dissipation: Power lost within the battery due to internal resistance: $P = I^2r$.
• 🧮 Calculating Internal Resistance: If you know the EMF, terminal voltage, and current, you can find the internal resistance using: $r = \frac{\varepsilon - V_T}{I}$.
• 🔑 Key takeaway: Internal resistance affects the efficiency and voltage delivered by a power source.

🧪 Practice Quiz

1. A battery with an EMF of 12V has a terminal voltage of 11.4V when delivering a current of 3A to a circuit. What is the internal resistance of the battery?
   1. 0.1 Ω
   2. 0.2 Ω
   3. 0.3 Ω
   4. 0.4 Ω
2. What happens to the terminal voltage of a battery as the current drawn from it increases?
   1. It increases.
   2. It decreases.
   3. It remains constant.
   4. It fluctuates randomly.
3. A battery has an EMF of 9V and an internal resistance of 0.5Ω. What is the terminal voltage when a 1.5A current is flowing?
   1. 7.5 V
   2. 8.25 V
   3. 9.75 V
   4. 6.75 V
4. Which of the following factors does NOT affect the internal resistance of a battery?
   1. Temperature
   2. Electrolyte concentration
   3. Size of the electrodes
   4. External circuit resistance
5. What is the power dissipated due to the internal resistance of a battery with an internal resistance of 0.2Ω and a current of 5A?
   1. 2 W
   2. 5 W
   3. 10 W
   4. 25 W
6. A battery with an internal resistance of 1Ω is connected to a 5Ω resistor. If the EMF of the battery is 6V, what is the current flowing in the circuit?
   1. 0.5 A
   2. 1 A
   3. 1.2 A
   4. 2 A
7. If the internal resistance of a battery is zero, what is the relationship between the EMF and the terminal voltage?
   1. Terminal voltage is greater than EMF.
   2. Terminal voltage is less than EMF.
   3. Terminal voltage is equal to EMF.
   4. There is no relationship.