Cacculate the resissivity of the amterial of a wire 1.0 m long, 0.4 mm in diameter and having a resistance of 2.0 ohm.

Explanation

Resistivity `(rho) = ?`
Length (l)= 1.0 m
Diameter = 0.4 mm
Radius of wire = r = `(0.4)/2= 0.2` mm
`= 0.2 xx10^(-3) m`
`r= 2 xx10^(-4) m `
Resistance = R= 2.0 ohm
`R = rho(l)/A`
`R = rho (l)/A`
`rho =(RA)/(l)=R/l(pir^2)[ :. A = pir^2]`
`rho=2/1xx22/7 xx(2xx10^(-4))^2=25.14xx10^(-8)`
`rho = 2.514 xx10^(-7)Omegam`