The length of a conducting wire is 50 cm and its radius is 0.5 mm. If its resistance is `30 Omega` what is the resistivity of its material?

Explanation

`L = 50 cm = 50 xx10^(-2) m`
`r = 0.5 mm = 0.5 xx10^(-3) m`
`=5xx10^(-4) m and R =0.5xx10^(-3) m`
`= 5xx10^(-4) m and R = 30 Omega`
Resistivity `rho =(RA)/(L) and A = pi r^(2)`
`therefore rho = R (pi r^(2))/(L)`
`=(30 xx 3.14 xx(5xx10^(-4))^(2))/(50xx10^(-2))`
`(30xx3.14xx25xx10^(-8))/(50xx10^(-2))`
`=47.1 xx 1-^(-6) Omega m`
`=4.71xx10^(-5) Omega m`
`therefore` Resistivity of the wrie `4.71xx10^(-5) Omega m`