Question

Calculate the resistivity of a metal of length 2m at 20°C having the resistance of 20Ω and diameter 0.3mm?

Answer 1

R = 20 ohm

l = 2m = 2000mm

d = 0.3mm =
r= d/2 = 0.3/2 = 0.15mm

Cross-section Area = pi×r^2 = 22/7 × 0.0225

= 0.070mm^2

Resiativity = AR / l

= 0.070 × 20 / 2000

= 0.0007 = 7.0 × 10^-4 ohm mm



Thanks

Answer 2

Answer:

Explanation:

R=20 ohm

l=2m=2000mm

d=0.3/2=0.15mm

area of cross section=pier^2

                                  =22/7*(0.15)^2

                                  22/7*0.0225

                                   =0.07mm^2

p=RA/l

=20*0.07/2000

=0.07/100

=7*10^-4 ohm meter