Two metallic wires of the same metal whose masses are 12g and 18g have lengths in the ratio 3:4 .Their resistances are in the ratio

Options

A. `4 :3`
B. `9 :18`
C. `18 :27`
D. `27 :32`

Answer

D

Explanation

`3l Ad =12`
` and 4l A_1 d=18`
` therefore (3A)/(4A_1) =(2)/(3) or (A)/(A_1) =8/9`
Now (`R_1) /(R_2) = ( rho xx 3l)/( A) xxx (A_1)/(rho xx 4l)`
` =3/4 xx 9/8 =(27)/(32)`