Internal resistance

Definition

Internal resistance is the opposition to the flow of electric current within a power source, such as a battery or cell. It plays a crucial role in determining the overall efficiency and performance of the power source, affecting the voltage output under load. High internal resistance can lead to significant voltage drops and decreased power delivery when the device is used in practical applications.

5 Must Know Facts For Your Next Test

1. Internal resistance is typically measured in ohms and varies with factors like temperature, age, and charge state of the power source.
2. As internal resistance increases, the efficiency of a battery decreases because more energy is wasted as heat instead of being delivered to the load.
3. Batteries with low internal resistance are preferred for applications requiring high current output since they can deliver more power without significant voltage loss.
4. When testing a battery, measuring its open-circuit voltage versus its loaded voltage can help determine its internal resistance.
5. Understanding internal resistance is vital for optimizing battery performance in applications like electric vehicles and renewable energy systems.

Review Questions

• How does internal resistance affect the performance of a battery when supplying current to a load?
  • Internal resistance negatively impacts battery performance by causing voltage drops when current flows. This means that under load, the actual voltage available to the external circuit is lower than the battery's open-circuit voltage. Consequently, higher internal resistance can result in reduced efficiency and power delivery, which can be critical in applications requiring consistent energy supply.
• Compare and contrast internal resistance with load resistance in a simple electrical circuit.
  • Internal resistance refers to the inherent opposition within a power source that affects how well it can deliver current, while load resistance is the opposition presented by external components consuming that current. In an electrical circuit, both resistances play crucial roles; however, internal resistance can lead to inefficiencies by reducing the effective voltage supplied to the load, whereas load resistance determines how much current flows based on Ohm's Law.
• Evaluate the implications of high internal resistance in battery systems used for renewable energy applications.
  • High internal resistance in batteries used for renewable energy systems can severely limit their effectiveness. It leads to significant energy losses as heat, reducing overall efficiency and making it harder to store and deliver power during peak usage times. This inefficiency can undermine system performance and longevity, potentially leading to increased operational costs and reduced reliability, emphasizing the importance of choosing batteries with low internal resistance for these applications.

Related terms

Electromotive Force (EMF): The energy provided by a power source per coulomb of charge, typically measured in volts, representing the potential difference that drives current through a circuit.

Load Resistance: The resistance presented by an external component or circuit that consumes power from a power source, influencing the total current and voltage output.

Voltage Drop: The reduction in voltage across a component in a circuit due to resistance, which can be significant in cases of high internal resistance.