Q.

A metal wire has mass (0.4±0.002) g, radius (0.3±0.001) mm and length (5±0.02) cm. The maximum possible percentage error in the measurement of density will nearly be      [2023]

1 1.6%  
2 1.4%  
3 1.2%  
4 1.3%  

Ans.

(1)

Volume of the wire, V=πr2L

Density of the wire ρ=mV=mπr2L

For percentage error,

Δρρ×100=Δmm×100+2×Δrr×100+ΔLL×100

  Δρρ×100=0.0020.4×100+2×0.001×1000.3+0.025×100

=0.5+0.67+0.4=1.571.6%