Question
What is the electric resistance and resistivity ?
✓
Answer
$\rightarrow $ "The electrical resistance of any object is directly proportional to its length. $1,$ and inversely proportional to its area of cross section $, A."$
$\rightarrow R \propto \frac{l}{A}$
$\therefore R =\rho \cdot \frac{l}{A}$
Where, $\rho=$ Resistivity $(Or)$ specfic resistance
$\rightarrow$ The electrical resistance is represented by the symbol $'R\ '$ and it is measured in ohm $(\Omega)$
$\rightarrow SI$ unit is $kgm ^2 / s ^3 \cdot A ^2$
$\rightarrow$ It can be measured with the help of awheatstone bridge.
$\rightarrow$ "The resistivity for a substance is its resistance when it is one metre long and its area of cross section is one $m^2."$
$\therefore \rho= R \left(\frac{ A }{l}\right) $
$\rightarrow$ Its $SI$ units are ohm metre $(\Omega M )$ and quite often its submultiple. ohm centimetre
$( \Omega \ \ cm )$ is also used.
$1 \Omega\ m =100 \ \ \Omega \ cm$ or $1 \Omega \ cm =0.01 \ \Omega \ m$
$\rightarrow R \propto \frac{l}{A}$
$\therefore R =\rho \cdot \frac{l}{A}$
Where, $\rho=$ Resistivity $(Or)$ specfic resistance
$\rightarrow$ The electrical resistance is represented by the symbol $'R\ '$ and it is measured in ohm $(\Omega)$
$\rightarrow SI$ unit is $kgm ^2 / s ^3 \cdot A ^2$
$\rightarrow$ It can be measured with the help of awheatstone bridge.
$\rightarrow$ "The resistivity for a substance is its resistance when it is one metre long and its area of cross section is one $m^2."$
$\therefore \rho= R \left(\frac{ A }{l}\right) $
$\rightarrow$ Its $SI$ units are ohm metre $(\Omega M )$ and quite often its submultiple. ohm centimetre
$( \Omega \ \ cm )$ is also used.
$1 \Omega\ m =100 \ \ \Omega \ cm$ or $1 \Omega \ cm =0.01 \ \Omega \ m$
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