A wire has a mass `0.4 +- 0.004g` and length `8 +- 0.08(cm)` The maximum percentage error in the measurement of it density is `4%` The radius of the wire is `r +- Delta r` find `Delta r`

Options

A. `0.02r`
B. `0.01 r`
C. `0.03r`
D. `0.1r`

Answer

B

Explanation

`rho= (m)/(pi r^(2)L)`
`(Delta rho)/(rho) xx 100[((Delta m)/(m)+ 2 (Delta r)/(r ) + Delta L)/(L)]xx 100`
`= (0.01 + 2(Delta r )/(r ) + 0.01) xx 100 = 4`(given)
`or `100(Delta r)/(r ) = 1`
`Delta r = 0.01r`