Question

the resistance (r) in a wire increases when the length of the wire (l) increases. write the correct equation for this scenario, and solve for when the length is 1.

Answer 1

Hello,

This is the law of Pouillet.

$r=\rho* \dfrac{L}{S}\\ if \ L=1\ then\ \boxed{r= \dfrac{\rho}{S} }$

Answer 2

Answer:

$r=\frac{\rho}{A}$

Step-by-step explanation:

Given,

Resistance (r) in a wire increases when the length of the wire (l) increases,

That is, r is proportional to l

$r\propto l$    

Also, we know that Resistance is inversely proportional to the cross sectional area, A,

That is,

$r\propto \frac{1}{A}$

By combining,

$r\propto \frac{l}{A}$

$r=\rho \frac{l}{A}$

Where, $\rho$ is the resistivity constant.

Given, l = 1 unit,

Hence, the required formula would be,

$r=\frac{\rho}{A}$