Resistance and Resistivity?

Question

A wire 6.24 m long with a diameter of 2.00 mm has a current of 0.500 A when it is connected to a better of five 1.5 V dry cells in series. Calculate the wires (a) resistance and (b) resistivity.

Answer 1

Solution:
R=V/I (resistance) = 3ohms
A=PiD^2/4 (cross sectional area) = 10E-6 M^2
Resistivity Rs = (RA)/l=
(V/I)( PiD^2/4)/l=
(3)(10e-6 Pi)/6.24=~
1.5e-6 ohms meters
If my calculations are correct the material is Nichrome 1.50 × 10E-6


A little theory
Resistivity is a material constant (like its density) while resistance is a measurement associated with a particular specimen (like its mass).

Electrical resistivity is measure of how a conductor opposes the flow of electric current.
As you know the flow is proportional to the materials constant and its cross sectional area and is inversely proportional to the material’s length.

Rs=RA/l where
Rs- resistivity
R – electrical resistance of the material
L – length of the material specimen

Resistance is simply voltage across the specimen divided by the current flowing across it.

R=V/R (the famous Ohm's Law)

I hope it was helpful.

Answer 2

resistence = e=ir 7.5=.5 r = 7.5/.5=r 15 ohms = r
resistence = 15 ohms

resistivity = r/l = 15/6.24 =2.4 ohms per meter