Converting the diameter for the equation l = RA/rho

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To determine the length of an aluminum wire needed to create a 20 Ohm coil, the diameter must first be converted from 0.5 mm to meters, resulting in 0.0005 m. The formula l = RA/rho is used, where R is resistance, A is the cross-sectional area, and rho is resistivity. The cross-sectional area A can be calculated using the diameter, with A = π(d/2)². The resistivity of aluminum is given as 2.8 x 10^-6 Ohm cm, which should be converted to Ohm m for consistency in units. Understanding these conversions and calculations is essential for solving the problem accurately.
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Homework Statement



An aluminium wire has diameter 0.5 mm and resistivity 2.8 X 10-6 Ohm cm. How much lenth of this wire is required to make a 20 Ohm coil?

Please tell me how to convert Diameter 0.5mm? what's the procedure?
After that I can directly apply-
l = RA/rho
 
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vikz said:

Homework Statement



An aluminium wire has diameter 0.5 mm and resistivity 2.8 X 10-6 Ohm cm. How much lenth of this wire is required to make a 20 Ohm coil?

Please tell me how to convert Diameter 0.5mm? what's the procedure?
After that I can directly apply-
l = RA/rho


What do each of your variables signify, R, A, rho?
 
sjb-2812 said:
What do each of your variables signify, R, A, rho?

R = Resistance
rho= Electrical Resistivity of the material of the conductor.
A = Area of cross-section

SI unit of resistivity is Ohm m
 
Last edited:
vikz said:
R = Resistance
rho= Electrical Resistivity of the material of the conductor.
A = Area of cross-section

Which of those variables depends directly the radius (or diameter) of the wire?
 
gneill said:
Which of those variables depends directly the radius (or diameter) of the wire?

R is inversely propositional to 1/A
 
Last edited:
Suppose that d=0.5mm is the diameter of the wire. What is the cross sectional area, A?
 

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