Potential Drop Across Resistor - Explained

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SUMMARY

The discussion clarifies the concept of "potential drop" across a resistor, emphasizing that a decrease in current does not imply a decrease in voltage. It explains that in a circuit with a single battery and a resistor, the potential drop is defined by the voltage difference across the resistor. In series circuits, the voltage drop is divided among resistors based on their resistance values, adhering to Ohm's Law (V = IR). This fundamental understanding is crucial for analyzing electrical circuits.

PREREQUISITES
  • Understanding of Ohm's Law (V = IR)
  • Basic knowledge of series and parallel circuits
  • Familiarity with voltage and current concepts
  • Concept of voltage dividers in electrical circuits
NEXT STEPS
  • Study Ohm's Law applications in various circuit configurations
  • Learn about voltage dividers and their practical applications
  • Explore series and parallel resistor combinations in detail
  • Investigate the effects of varying resistance on current and voltage in circuits
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Electrical engineering students, hobbyists working with circuits, and anyone seeking to deepen their understanding of voltage and current relationships in electrical systems.

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When one says there is a "potential drop" across the resistor, they do not mean the actual voltage has gone down right? They just mean the current has? But then I question that because since the current goes down then the voltage has to as well? I am fuzzy on this subject, can you explain? Why is there a potential drop? Just because the current goes down?
 
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Voltage "goes down"

Yes, they do.

For example, consider a single battery, and a single resistor in parallel. The voltage at the + side of the battery is +V, and the voltage at the - side of the battery is zero volts. The difference (potential drop) would be V.

For two equal value resistors in series with the same battery half of the voltage drops across each resistor. For unequal resistances in series, you have a voltage divider. The current through both is the same and V = IR, so what do you think will happen?
 

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