physics
posted by lynette .
Suppose that you wish to fabricate a uniform wire out of 0.900 g of copper. Assume the wire has a resistance R = 0.500 , and all of the copper is used.
(a) What will be the length of the wire? (m)
(b) What will be the diameter of the wire? (µm)

You have two simultaneous equations to solve, and they depend upon the resisitivity and the density, which you will have to look up.
1)0.500 ohms = (resistivity)*L/(pi*D^2/4)
2)0.900 g = (density)*L*pi*(D^2/4)
I suggest using centimeter, g/cm^3 and ohmcm units.
The product of mass and resistance, which you know, will let you solve for L. 
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