Internal resistance of a battery

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SUMMARY

The discussion focuses on calculating the internal resistance of a battery using two different resistances and their corresponding currents. The first scenario involves a 10.5-ohm resistance with a current of 2 amps, while the second scenario uses a 48-ohm resistance with a current of 0.5 amps. The equation E = I(R + r) is utilized to derive the internal resistance (r) of the battery, where E represents the electromotive force (EMF). By setting up two equations based on the given values, one can solve for both EMF and internal resistance simultaneously.

PREREQUISITES
  • Understanding of Ohm's Law
  • Familiarity with the concept of electromotive force (EMF)
  • Knowledge of circuit analysis techniques
  • Ability to solve simultaneous equations
NEXT STEPS
  • Study the derivation of Ohm's Law and its applications in circuit analysis
  • Learn how to calculate EMF in electrical circuits
  • Explore methods for solving simultaneous equations in physics
  • Investigate the impact of internal resistance on battery performance
USEFUL FOR

Students in physics, electrical engineers, and anyone involved in battery technology or circuit design will benefit from this discussion.

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Ok guys I need help! Its been a while since I last opened a physics workbook and now I'm back to studying to try and further my career and I've come across an internal resistance question that I can't get my head around!

A resistance of 10.5 ohms is connected across the terminals of a battery and a current of 2 amps flows. When this resistance is replaced by another resistance of 48 ohms a current of 0.5 amps flows. The internal resistance of the battery therefore equals?

The only equation I've come up with is E = I(R+r)

So to work out the internal resistance of the battery I need to work out the emf first to use the above equation but how do I do that? I thought of using similar equations but that will only work if there is one unknown in the equation not two right?
 
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You can set up two such equations with the two values of resistance and current. Assuming the battery EMF doesn't change, you can then solve the 2 equations for EMF and internal resistance.
 

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