Calculate the resistance of iron if

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SUMMARY

The resistance of a rectangular bar of iron with a cross-sectional area of 2cm by 2cm can be calculated using the formula R = ρl/A, where ρ is the resistivity of iron, given as 11 × 10-8 Ωm. However, the length (l) of the bar is essential for calculating the total resistance. Without the length, the resistance can only be expressed per unit length using the formula R/ℓ = ρ/A.

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Homework Statement


A rectangle bar of iron is [tex]2cm[/tex] by [tex]2cm[/tex] in cross section. Calculate its resistance if the resistivity of iron is [tex]11 \times 10^{-8}\Omega{m}[/tex].

Homework Equations



[tex]R = \frac{Pl}{A}[/tex]

The Attempt at a Solution



[tex]R = \frac{Pl}{A}[/tex]

[tex]A = 2 \times 2 \times 10^-4 = 4 \times 10^{-4}m[/tex]
[tex]P = 11 \times 10^{-8}\Omega{m}[/tex]

How is it possible to find the resistance If I don't have the length?
 
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looi76 said:

How is it possible to find the resistance If I don't have the length?


It isn't.

Maybe they are looking for the resistance per unit length:

[tex]\frac{R}{\ell}=\frac{\rho}{A}[/tex]
 

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