Two wires that are made up of two different materials whose specific resistance are in the ratio 2 : 3, length 3 : 4 and area 4 : 5. The ratio of their resistances is

Options

A. `6:5`
B. `6:8`
C. `5:8`
D. `1:2`

Answer

C

Explanation

`rho_(1) = 2rho, rho_(2) = 3 rho, I_(1) = 3I, I_(2) = 4l`
`A_(1) = 4A, A_(2) = 5A`
`R_(1)/R_(2) = (2rho xx 3l)/(4A) xx (5A)/(3 rho xx 4l) = 5/8`