Does Ohm's Law Equate to the Resistivity Formula R = ρ(L/A)?

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SUMMARY

Ohm's Law, defined as R = V/I, is fundamentally related to the resistivity formula R = ρ(L/A), where ρ (rho) represents resistivity, L is the length, and A is the cross-sectional area. The discussion clarifies that while resistivity can affect current flow in a circuit, one cannot isolate the current in a resistor from the overall circuit dynamics, as the total current is determined by the total resistance, including that of the wiring and battery. Additionally, not all materials conform to Ohm's Law, as resistance can vary with voltage and temperature, making the resistivity relationship empirical rather than universally applicable.

PREREQUISITES
  • Understanding of Ohm's Law (R = V/I)
  • Familiarity with the resistivity formula (R = ρ(L/A))
  • Basic knowledge of electrical circuits and components
  • Awareness of material properties affecting electrical resistance
NEXT STEPS
  • Study the relationship between voltage, current, and resistance in series and parallel circuits
  • Explore the concept of resistivity in different materials, focusing on metals like copper and aluminum
  • Investigate the effects of temperature on resistance in various materials
  • Learn about non-ohmic materials and their behavior in electrical circuits
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Students, electrical engineers, and educators seeking a deeper understanding of circuit behavior, resistivity, and the limitations of Ohm's Law in practical applications.

Chromium
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1st question
Ohm's Law is R = V/I; however there is another law that states : R = p (L/A) (the p should be a rho, i know)


so this means that V/I = p (L/A) ?


2nd question
A resistor in a circuit can have a smaller current in it than the actual wire because of a higher resistivity, right? Example if the circuit's wires are copper, but there is a resistor that has a higher resistivity (like aluminum), will the resister have a smaller I than the copper?
 
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To your second question, no. You can't simply separate circuit components like that. The actual current that flows through the circuit is the battery voltage V divided by the total circuit resistance which is R + the resistance (albeit very small) of the copper wire + the battery's internal resistance.

Imagine a circuit with two resistors of different values in series. Would it make sense that there is more current flowing in one resistor than the other? Where would this "extra" current disappear to between them?

Ohm's Law is an interesting observation relating the voltage and current in a circuit. Not all materials obey Ohm's Law. In fact, resistance of most real materials are to a certain degree voltage and temperature dependent. The other relationship you mention for the calculation of resistivity is more or less empirical. We deduce this relationship.
 

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