a length of #8 copper wire (radius = 1.63 mm) has a mass of 24.0 Kg and a resistance of 2.061 Ohm per Km. What is the over all resistance of the wire?
V = m / ρ
V = (23,200/8.96) × 1000
V = 2,589,285.71 mm³
Now we have volume and given the radius we can solve for its length.
L = V/πr²
L = (2,589,285.71/(π×1.63²))/1×10^6
L = 0.31 km
So
R = rL
R = 2.061(0.31)
R = .6389 Ω
End.
Answer : The overall resistance of the wire is \(6.617\times 10^{-4}ohm\)
Explanation :
First we have to determine the volume of copper wire.
Density of copper wire = \(0.00896kg/mm^3\)
\(Volume=\frac{Mass }{Density}=\frac{24kg}{0.00896kg/mm^3}=2678.57mm^3\)
Now we have to determine the area.
\(Area=\pi r^2\)
where,
r = radius of copper wire = 1.63 mm
\(Area=3.14\times (1.63mm)^2=8.343mm^2\)
Now we have to determine the length of the wire.
\(\text{Length of the wire}=\frac{\text{Volume of wire}}{\text{Area of wire}}\)
\(\text{Length of the wire}=\frac{2678.57mm^3}{8.343mm^2}=321.06mm=3.2106\times 10^{-4}km\)
conversion used : \((1mm=10^{-6}km)\)
Now we have to determine the overall resistance of the wire.
\(\text{Overall resistance}=\text{Length of wire}\times \text{Resistance of wire}\)
\(\text{Overall resistance}=3.2106\times 10^{-4}km\times 2.061ohm/km\)
\(\text{Overall resistance}=6.617\times 10^{-4}ohm\)
Therefore, the overall resistance of the wire is \(6.617\times 10^{-4}ohm\)