How many number of turns of nichrome wire of specific resistance `10^(-6)Omegam` and diameter 2mm that should be wound on a cylinder of diameter 5cm to obtain a resistance of ?

Explanation

If R is the radius of the cylinder
r is the radius of the wire and
N is the number of turns
`"then "R.=(rhol)/(A)" "therefore" "R.=(rho(2piR)N)/(pir^(2))`
`40=(10^(-6)(2xx2.5xx10^(-2)xxN))/(1xx10^(-6)) therefore N=800`