Solving Electromotive Force Homework: 5000V Power Supply & 20kohm Voltmeter

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SUMMARY

The discussion centers on a homework problem involving a power supply with an electromotive force (emf) of 5000V and a voltmeter with a resistance of 20kΩ, which reads only 24V when connected. The discrepancy is attributed to the internal resistance of the power supply, creating a voltage divider effect. Participants suggest analyzing the circuit diagram and calculating the internal resistance to understand the voltage drop observed across the voltmeter.

PREREQUISITES
  • Understanding of electromotive force (emf) and voltage readings
  • Knowledge of Ohm's Law and resistance calculations
  • Familiarity with voltage dividers in electrical circuits
  • Basic circuit diagram drawing skills
NEXT STEPS
  • Calculate the internal resistance of the power supply using the voltage divider formula
  • Explore the impact of load resistance on voltage readings in circuits
  • Learn about circuit analysis techniques for complex circuits
  • Review the principles of electromotive force and its applications in real-world scenarios
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Students studying electrical engineering, physics enthusiasts, and anyone tackling circuit analysis problems involving voltage and resistance.

caltzx
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Homework Statement



A power supplyused in a lab has an emf of 5000V. However, when a voltmeter of resistance 20kohm is connected to the terminal of the power supply, a reading of only 24V is obtained. Explain this conservation and calculate any necessary quantity.

The Attempt at a Solution



Not really sure where to go with this. I think it has something to do with internal resistance and such but... not really sure. Could someone at least point me in the right direction?

Thank you.
 
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Maybe start by drawing a circuit diagram.

You have a box that nominally has 5000V.

But when you effectively put a 20KΩ load across it, it only reads 25V.

So what you apparently have is some kind of voltage divider.

Perhaps you want to consider some internal resistance?
 

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