Two wires A and B of the same material have their lengths in the ratio `5: 3` and diameter in the radius `2:3`. If the resistance of wire A is `15 Omega`. find the resistance of wire B

Answer

`4 Omega`

Explanation

`R = (4 rhol)/(pi D^(2)) or R = (l)/(D^(2))`
`:.(R_(2))/(R_(1)) = (l_(2))/(l_(1)) xx (D_(1)^(2))/(D_(2)^(2)) = (3)/(5) xx ((2)/(3))^(2) = (4)/(15)`
or `R_(2) = (4)/(15) R_(1) = (4)/(15) xx 15 = 4 Omega`