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Resistance of a piece of metal

  • Thread starter 05holtel
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  • #1
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Homework Statement




How does the resistance of a piece of metal change if both its length and its diameter are reduced to one half their original values?
Question 1 answers
It is increased to 4 times the original value
It doubles
It remains unchanged
It is halved
It is reduced to 1/4 of the original value

Homework Equations



R = pL/A where P is the resistivity constant

The Attempt at a Solution



I am not sure how to relate the area to change in area
 

Answers and Replies

  • #2
1,953
248


The Attempt at a Solution



I am not sure how to relate the area to change in area
I think you can assume it's a round wire.
 
  • #3
lightgrav
Homework Helper
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they call one dimension a "diameter" , which becomes half
... how does the new Area compare to the old Area ?
(it's not about _change_ , it is about new = "some number" times old)
 
  • #4
1,953
248


they call one dimension a "diameter" , which becomes half
... how does the new Area compare to the old Area ?
(it's not about _change_ , it is about new = "some number" times old)
Assume it's a round wire, with diameter d, the new diameter will be d/2.
old length is L, new length is 2L

Calculate old and new resistance, compare.
 

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