How do I know what the internal resistance of a battery is in a diagram?

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SUMMARY

The internal resistance of a battery in a circuit diagram is conventionally represented by a resistor labeled "r" adjacent to the battery. In this case, the terminal voltage can be calculated using the formula V = IR, where V is the battery voltage minus the voltage drop across the internal resistance. The voltage drop is determined by the current (I) flowing through the internal resistance (R). Understanding this convention is crucial for accurately analyzing battery performance in electrical circuits.

PREREQUISITES
  • Basic understanding of Ohm's Law (V = IR)
  • Familiarity with circuit diagrams and components
  • Knowledge of battery characteristics and behavior
  • Concept of terminal voltage in electrical circuits
NEXT STEPS
  • Study the concept of internal resistance in batteries
  • Learn how to calculate terminal voltage in various circuit configurations
  • Explore the impact of internal resistance on battery performance
  • Investigate common conventions used in electrical circuit diagrams
USEFUL FOR

Students studying electrical engineering, educators teaching circuit analysis, and anyone interested in understanding battery characteristics and their implications in circuit design.

chiddler
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Homework Statement


I am trying to find terminal voltage of the batteries in the circuit shown.

Homework Equations



V = IR

The Attempt at a Solution



The solution manual says that it's the battery voltage, v, minus the voltage drawn from the resistance v = I * R. I understand this.

I do not understand how I'm supposed to know that the 1 ohm resistor adjacent to each battery corresponds to the battery's internal resistance. I would very much appreciate help with this. Thank you!
 

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It's labeled with "r". There's no rhyme or reason to this; it's just convention that whenever you see a resistor labeled "r" beside a battery, you should assume that it's internal resistance.
 

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