Resistance of a piece of metal

[05holtel]

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

 

[willem2]

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.

 

[lightgrav]

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)

 

[willem2]

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.