A wire of length l, area of cross section A and resistance R is stretc

1.	A wire of length l, area of cross section A and resistance R is stretched so that thelength is doubled. How will its resistance and resistivity change?
Answer» $\color{darkblue}\underline{\underline{\sf Given-}}$ LENGHT of wire = $\ell$ Cross SECTION area of wire = A Resistance = R Then , Lenght is doubled = 2 $\ell$ $\color{darkblue}\underline{\underline{\sf To \: Find-}}$ Resistance (R) RESISTIVITY ${\sf (\rho)}$ $\color{darkblue}\underline{\underline{\sf Solution-}}$ $\color{violet}\bullet\underline{\boxed{\sf R =\rho\dfrac{\ell}{A}}}$ Resistance is DIRECTLY proportional to Lenght of wire $\implies{\sf R\: \: \propto\:\:\ell}$ $\implies{\sf R \: \: \propto\:\;\dfrac{1}{A}}$ Therefore, if $\ell$ will be double then Resistance (R) will also doubled 2R $\color{darkblue}\underline{\underline{\sf Answer-}}$ Resistance will be doubled (2R) Resistivity will be same because it's CONSTANT.