Question

The resistance of copper wire 25 metres long is found to be 50 ohms if diameter is 1 mm, calculate the resistivity of the copper

Answer 1

Answer:

the resistivity=1.57×10^-6

Explanation:

given value

L=25m

R=50ohm

D=1×10^-3

so r=0.5 10^-3=5×10^-4m

CALCOLATION

resistivity=RA/L

=50×(3.14 ×25×10^-8)/25

=1.57×10^-6omh.m

Answer 2

Answer:

we know that:

R=50 ohm

l=25m

d=1mm

d=0.0001m

r=0.00005m

and we know that:

resistance=rho×l/A

50=rho×25/πr^2

50= rho×25/3.14×0.00005^2

rho=50×3.14×0.00005^2

rho=157×0.000025

rho=0.003925

rho=3.9×10^3 (approximately)