Question

Define the term resistivity.

Answer 1

Hint: In electricity, the materials which oppose the flow of electric current passing through them are known as resistors and this property of opposing flow of electric current is called resistance. Resistance is a scalar quantity and it’s measured in the units of Voltage per ampere or simply denoted as ohm with the symbol of $\Omega $.

Complete step by step answer:
According to the definition of resistivity, resistivity is the amount of resistance offered by the conductor whose length is of $1m$ an area of cross section is $1{m^2}$ and mathematically resistivity is calculated as
$\rho = \dfrac{{RA}}{L}$
Where, $R$ is the resistance of the conductor whose SI unit is $\Omega $, $A$ is the area of cross section of the conductor having SI units of ${m^2}$ and $L$ is the length of the conductor having SI unit of $m$.

So, the SI unit of resistivity became $\dfrac{{\Omega {m^2}}}{m}$. $\Omega m$ Which is read as ohm meter. And resistance of the material is depends upon the voltage applied and current flowing across the material and its magnitude is determined by using ohm’s law which is written as,
$R = \dfrac{V}{I}$
So, the another formula of resistivity can be written as,
$\therefore \rho = \dfrac{{VA}}{{IL}}$

Note: It should be remembered that resistance of the material always depends upon the applied voltage and current flowing across the material but in electrical circuits nowadays, resistors are pre made available in the market used with their fixed amount of resistance offered as per required in the electrical circuits. Resistivity of the metals increases with increase in temperature and the resistivity of semiconductors like silicon and germanium decreases with increase in temperature and some insulators converted into conductors at high temperature as resistivity decreases with increase in temperature for some non-metals.