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Wrichik Basu
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True, $A$ and $L$ are involved. But resistivity is a constant.

In the equation $$\rho = \frac{R A}{L}$$ if you change the resistance and length of conductor and then experimentally measure the resistance, and put it in the formula, you'll find that the resistivity has remained a constant for all different $A$ and $L$, because $R$ gets suitable modified to keep resistivity constant.

This is an experimental result. I remember trying this out myself, and the results showed that resistivity is a constant.

For another example, consider this formula for Coloumb's law: $$ F = \frac{1}{4\pi \epsilon _0} \frac{q_1 q_2}{r^2}$$ where $\epsilon _0$ is the permittivity of free space. Now, you can aptly write $$ \epsilon _0 = \frac{1}{4\pi F} \frac{q_1 q_2}{r^2}$$ and say that it is not a constant. But experiments show that for different values of $q_1$, $q_2$ and $r$, the force $F$ varies such that permittivity $\epsilon _0 $ remains a constant for a particular material, at a particular temperature.

True, $A$ and $L$ are involved. But resistivity is a constant.

In the equation $$\rho = \frac{R A}{L}$$ if you change the resistance and length of conductor and then experimentally measure the resistance, and put it in the formula, you'll find that the resistivity has remained a constant for all different $A$ and $L$, because $R$ gets suitable modified to keep resistivity constant.

This is an experimental result. I remember trying this out myself, and the results showed that resistivity is a constant.

For another example, consider this formula for Coloumb's law: $$ F = \frac{1}{4\pi \epsilon _0} \frac{q_1 q_2}{r^2}$$ where $\epsilon _0$ is the permittivity of free space. Now, you can aptly write $$ \epsilon _0 = \frac{1}{4\pi F} \frac{q_1 q_2}{r^2}$$ and say that it is not a constant. But experiments show that for different values of $q_1$, $q_2$ and $r$, the force $F$ varies such that permittivity $\epsilon _0 $ remains a constant for a particular material.

True, $A$ and $L$ are involved. But resistivity is a constant.

In the equation $$\rho = \frac{R A}{L}$$ if you change the resistance and length of conductor and then experimentally measure the resistance, and put it in the formula, you'll find that the resistivity has remained a constant for all different $A$ and $L$, because $R$ gets suitable modified to keep resistivity constant.

This is an experimental result. I remember trying this out myself, and the results showed that resistivity is a constant.

For another example, consider this formula for Coloumb's law: $$ F = \frac{1}{4\pi \epsilon _0} \frac{q_1 q_2}{r^2}$$ where $\epsilon _0$ is the permittivity of free space. Now, you can aptly write $$ \epsilon _0 = \frac{1}{4\pi F} \frac{q_1 q_2}{r^2}$$ and say that it is not a constant. But experiments show that for different values of $q_1$, $q_2$ and $r$, the force $F$ varies such that permittivity $\epsilon _0 $ remains a constant for a particular material, at a particular temperature.

Source Link
Wrichik Basu
  • 2.9k
  • 6
  • 29
  • 41

True, $A$ and $L$ are involved. But resistivity is a constant.

In the equation $$\rho = \frac{R A}{L}$$ if you change the resistance and length of conductor and then experimentally measure the resistance, and put it in the formula, you'll find that the resistivity has remained a constant for all different $A$ and $L$, because $R$ gets suitable modified to keep resistivity constant.

This is an experimental result. I remember trying this out myself, and the results showed that resistivity is a constant.

For another example, consider this formula for Coloumb's law: $$ F = \frac{1}{4\pi \epsilon _0} \frac{q_1 q_2}{r^2}$$ where $\epsilon _0$ is the permittivity of free space. Now, you can aptly write $$ \epsilon _0 = \frac{1}{4\pi F} \frac{q_1 q_2}{r^2}$$ and say that it is not a constant. But experiments show that for different values of $q_1$, $q_2$ and $r$, the force $F$ varies such that permittivity $\epsilon _0 $ remains a constant for a particular material.