Are lost volts the difference between EMF and terminal potential difference?

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SUMMARY

The discussion clarifies that "lost volts" refer to the voltage drop between the electromotive force (EMF) and the terminal potential difference (pd) in electrical circuits. Specifically, in a typical scenario involving a voltage divider, the EMF of a cell is measured at 1.60V, while the terminal pd under load is 1.45V, resulting in lost volts of 0.15V. This value is often calculated as the product of the current through the supply and the internal resistance of the supply, particularly in educational contexts in the UK.

PREREQUISITES
  • Understanding of electromotive force (EMF)
  • Knowledge of terminal potential difference (pd)
  • Familiarity with voltage dividers
  • Basic concepts of internal resistance in electrical circuits
NEXT STEPS
  • Research the calculation of internal resistance in batteries
  • Learn about voltage divider circuits and their applications
  • Explore the relationship between current, voltage, and resistance using Ohm's Law
  • Investigate the effects of load on terminal potential difference in practical circuits
USEFUL FOR

Electrical engineering students, educators teaching circuit theory, and professionals involved in designing or analyzing electrical circuits will benefit from this discussion.

homeworkhelpls
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Are lost volts the difference between EMF and terminal pd?
 
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By "lost volts" I'm assuming you mean "voltage drop". Can you post a typical circuit that has generated this question?
 
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berkeman said:
By "lost volts" I'm assuming you mean "voltage drop". Can you post a typical circuit that has generated this question?
Actually its a general question, but the circuit used is say for example a potential divider
 
Okay, then what are "EMF" and "terminal pd" in the context of your question? The input battery voltage and the output of the 2-resistor voltage divider?
 
homeworkhelpls said:
Are lost volts the difference between EMF and terminal pd?
Maybe terminology varies regionally, but here in the UK that’s exactly what is meant by ‘lost volts’ for an electrical source.

E.g. a cell’s emf (measured open-circuit) is 1.60V. With some load, the p.d. between the cell’s terminals drops to 1.45V. Then the ‘lost volts’ = 1.60V - 1.45V = 0.15V.

The ‘lost volts’ value is often (especially for teaching and examination purposes here) taken to equal the product of the current through the supply and the supply’s notional internal resistance.
 
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