2) The resistance in a wire depends on:

 

 

a) resistivity - ρ  a metals structural resistance to electron flow

p. 4 Reference

 

b) Length (L) of the wire

 

 

 

c) Thickness (Cross Sectional Area) of the wire (A)

 

 

 

Why do large speakers
require thick speaker wire?

 

 

 

Answer: Large speakers draw a lot of current

 


 

R = ρL/A 

 

 

  

Ex) R, A relationship?

 

 

 

Inverse relationship

4 

 

 

 

 

Larger Version

 

 

 

 

3) Resistance and Temperature

(Double Click on Picture above to start video)

Full Size Video

 

Scientific Advisors: Dr. Saul Dushman; Dr. Roman Smoluchowski; Dr. David Harker

Prelinger Archives

Production Company: Wolff (Raphael G.) Studios, Inc. Audio/Visual: sound, color
Creative Commons license: Public Domain

 

 

 

 

 

 

 

 

Metals

 

T down, R down

 

T up, R up

 

 

 

 

(many electrical devices
 have fans to decrease T)

 

 


 

Nonmetals – When temperature increases, resistance decreases 

 

Superconductor - conductor with no resistance

 

Achieved only at very low temperatures (expensive now)

 

 

 

 

 

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