Question

the resistance of a wire of uniform cross-section is 100 ohms.the length of the wire is 5 m and its diameter is 0.04 cm.find the specific resistance of the material of the wire.

Answer 1

formula for resistance is R = specific resistance X length of materal \area of material 
 so 100 = specific resistance X 5\ pi R square 
100 = rho X 5 X 10000 \3.14 X 0.04 X 0.04     [:. 1 cm =   .001 m ]
100 = rho X 5 X 10000 \ 0.005024
100= rho X 9952229.29
100\9952229.29 =rho 
.000010048 ohm \ metre  = specific resistance{ rho    = specific resistance }

Answer 2

The answer is 2.512*10^-6 ohm/metre
spe.resistance(rho)=resistance(R)*area(A)/length(l)
rho=100*3.14*0.02*0.02/5*10000
rho=6.28*0.02/50000
rho=0.1256/50000
rho=0.000002512 ohm/metre
rho=2.512*10^-6 ohm/metre