Question

Part A) What is the resistance of a 1.8 mm -long copper wire that is 0.40 mmmm in diameter?

Part B) What is the resistance of a 14 cmcm -long piece of iron with a 1.0 mmmm ×× 1.0 mmmm square cross section?

Answer 1

We know resistance of any material is given by:

​​​​​​

where is resistivity of material, is length of material and A is Corsa section of it.

Part A

Given: l =1.8mm

d=0.4mm, r =0.2mm

so = 3.14 x 0.0002 x 0.0002 m^2

also we know resistivity of copper is 1.71x10^-8 ohm-m

Putting the values

Part B

l=14cm

A=1mmx 1mm

also we know resistivity of iron is 9.71x10-8 Ohm m

Putting the values in similar way we have