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Specific Resistance of Conductors
15 questions By Tony R. Kuphaldt
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Question 1 of 15
Given two lengths of metal wire, which one will have the least electrical resistance: one that is short, or one that is long? Assume all other factors are equal (same metal type, same wire diameter, etc.).
Reveal answerThe short wire will have less electrical resistance than the long wire.
Notes:Many analogies exist to express this concept: water through a pipe, compressed air through a hose, etc. Which pipe or hose is less restrictive: the short one or the long one?
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Question 2 of 15
Given two lengths of solid metal wire with round cross-sections, which one will have the least electrical resistance: one that is small-diameter, or one that is large-diameter? Assume all other factors are equal (same metal type, same wire length, etc.).
Reveal answerThe large-diameter wire will have less electrical resistance than the small-diameter wire.
Notes:Many analogies exist to express this concept: water through a pipe, compressed air through a hose, etc. Which pipe or hose is less restrictive: the skinny one or the fat one?
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Question 3 of 15
What is specific resistance, symbolized by the Greek letter “rho” (ρ)?
Reveal answerSpecific resistance is a measure of how resistive any particular substance is, relative to its length and cross-sectional area.
Notes:Ask your students, “Why is it important to have a quantity called specific resistance? Why don’t we just compare the “resistivity” of different substances in regular units of ohms?
