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Resistivity question help please? 10 points.?
Question: The resitivity of aluminium is twice that of copper. However, the density of aluminium is one-third that of copper.
a) For equal length and resistance calculate the ratio: mass of aluminium over mass of copper.
This topic isn't on density, it is on resitivity and ohm's and voltage and current etc.
If anyone could point me in the right direction I would greatly appreciate it.
Resitivity equation is: p = RA/L
Resitivity = p
Resitance = R
Cross-sectional area = A
Length = L
1 Answer
- ?Lv 79 years agoFavorite Answer
If length and resistance are equal, then the areas must be in proportion to the resistivities.
R = Lp/A
Lp1/A1 = Lp2/A2
p1/A1 = p2/A2
Since Aluminum has double the resistivity it needs to have double the area as well to come out to the same resistance. Given the same length, it necessarily has double the volume as well.
V(Al) = 2 V(Cu)
D = m/V
V = Dm
m(Al) D(Al) = 2 m(Cu) D(Cu)
m(Al)/m(Cu) = 2 D(Cu) / D(Al)
m(Al)/m(Cu) = 2 (3)
m(Al)/m(Cu) = 6