We have two wire `A` and `B` of the same mass and the same material. The diameter of the wire `A` is half of that `B`. If the resistance of wire `A` is `24 ohm` them the resistance of wire `B` will be

Options

A. `12 ohm`
B. `3.0 ohm`
C. `1.5 ohm`
D. None of the above

Answer

C

Explanation

(c ) Same mass, same material, i.e., volume is the same of `Al =` constant
` R = rho (l)/(A) implies (R_(1))/(R_(2)) = (l_(1))/(l_(2)) xx (A_(2))/(A_(1)) = ((A_(2))/(A_(1)))^(2) ((d_(2))/(d_(1)))^(4)`
`implies (24)/(R_(2)) = ((d)/(d//2))^(4) = 16 implies R_(1) = 1.5 Omega`