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Difficulty: EasyResistance and Resistivity

When comparing two electrical wires of identical length, diameter, and temperature, which material property determines which wire has lower electrical resistance?

  1. A
    Applied voltage
  2. ResistivityAnswer
  3. C
    Dielectric strength
  4. D
    Inductance

Answer

Resistivity is the material property that determines the electrical resistance of equal-dimensioned conductors.
Resistivity (represented by ρ\rho) is an intrinsic physical property of a material that measures its natural opposition to electric current flow. According to the formula R=ρLAR = \rho \frac{L}{A}, when two conductors share identical length (LL) and cross-sectional area (AA) at constant temperature, the wire made of a material with lower resistivity will have lower total electrical resistance.

Step-by-Step Solution

1
Apply the fundamental formula for conductor resistance: R=ρLAR = \rho \frac{L}{A}.
Total resistance (RR) is directly proportional to conductor length (LL), inversely proportional to cross-sectional area (AA), and directly proportional to resistivity (ρ\rho).
Because length, diameter (area), and temperature are held constant between the two wires, any difference in total resistance is strictly governed by the material's resistivity.
2
Identify the property representing the material's specific opposition to current.
Resistivity (ρ\rho) is the intrinsic characteristic of the substance.
A material with lower resistivity (such as copper compared to iron) will always yield a lower resistance when shaped into identical physical dimensions.

Key Concept

Resistance and Resistivity
Estimated Time:45s
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Topics

Resistance and Resistivity

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