Two conductors are made of the same material and have the same length. Conductor `A` is a solid wire of diameter `1 mm`. Conductor `B` is a hollow tube of outer diameter `2 mm` and inner diameter `1mm`. Find the ratio of resistance `R_(A)` to `R_(B)`.

Explanation

The resistance of first conductor
`R_(A)=(rhol)/(pi(10^(-3)xx0.5)^(2))`
The reisistance of second conductor,
`R_(B)=(rhol)/(pi[(10^(-3))^(2)-(0.5xx10^(-3))^(2)])`
Now, the ratio of two resistors is given by
`(R_(A))/(R_(B))=((10^(-3))^(2)-(0.5xx10^(-3))^(2))/((0.5xx10^(-3))^(2))=3:1`