Question

Resistance of a metal wire of length 2m is 26 Ohm at 20 degree Celcius. If the diameter of the wire is 0.2 mm, what will be its specific resistance ?​

Answer 1

answer.............

Given:      l = 1 m

                 d = 0.3 mm

                 A = om r2 = 3.14 x 2.25 x 10-8 = 7.065 x 10-8m2

Formula:        om = R x A / l

                            = 26 x 7.065 x 10-8

                            =183.69 x 10-8 om m

Thus, the resistivity of the metal wire at 20 om C is 183.69 x 10-8 om m.

please follow me.............

Answer 2

Explanation:

Resistance,R=26ohm length of wire,L=2m diameter of circular part of wire, d=0.2mm=0.2×10^-3m

so,base area of wire,A=πr^2=πd^2/4

[therefore,d=2r]=3.14×(0.2×10^-3)^2/4m^2=3.14×9×

10^-8/4m^2=28.26/4×10^-8

m^2=7.06×10^-8m^2

now use formula,

R=pL/A Here,R is the resistance,p is the resistivity,L is the length of wire and A is the base area of it.

so,p=RA/L=26ohm×7.06×10^-8m^2/1mp=1.8356×10^-6ohm at 20°C