A copper wire has diameter 0.5mm and resistivity of `1.6xx10^(-8)Omega`m. what will be the length of this wire to make its resistance `10Omega`? How much does the resistance change if the diameter is doubled ?

Explanation

`d = 0.5 mm = 0.5xx10^(-3) m`
= `1.6xx10^(-8) Omega` m
R `=10 Omega`
l= ?
`implies R prop (1)/(d^(2))`
If diameter gets doubled resistance will become `(1)/(4)` time i.e., `(1)/(4) xx10 = 2.5 Omega`