Question

Find the resistivity of a wire of length 1m and radius 0.2mm and resistance 20 ohm

Answer 1

l = 1m r = 0.2 mm = 0.2 * 10-3 A =pie *r =3.14*(0.2*10 -3)2 R= 20 ohm R= [ rho *l ]/A Therefore, rho = R*A/l rho= 3.14*(0.2*10 -3)2 *20/ 1 = 3.14 * 0.04* 10-6 *20 = 2.512*10-6 ohm-m