Following figure shows cross-section through three long conductors of the same length and material, with square cross-section of edge lengths as shown. Conductor `B` will snugly within conductor `B`. Relationship between their end to end resistance is

Options

A. `R_(A) = R_(B) = R_( C)`
B. `R_(A) gt R_(B) gt R_( C)`
C. `R_(A) lt R_(B) lt R_( c)`
D. Information is not sufficient

Answer

A

Explanation

If length is same then-
Area of cross section of `A = (sqrt(3)a)^(2) - (sqrt(2)a)^(2) = a^(2)`
Area of cross section of `B = (sqrt(2)a)^(2) - a^(2) = a^(2)`
Area of cross section of `C = a^(2)`
`R = (rho l)/A`. Since, l and A are same
`R_(A) =R_(B) =R_(C )`