The young's modulus of a material is ` 2xx10 ^(11) N//m^2 ` and its elastic limit is ` 1xx10 ^(8) N//m ^2` for a wire of 1m length of this material , the maximum elongation achievable is

Options

A. 0.2mm
B. 0.3mm
C. 0.4 mm
D. 0.5 mm

Answer

D

Explanation

Answer(4) Elongation of a material, I = `strain xx L
I = Stress/Y xx L` .
Young's modulus, `Y= 2 xx 10^11 N/m^2` .
Stress = `1 xx 10^8 N/m^2` .
Length = 1m `Rightarrow I = 10^8/(2 xx 10^11) xx 1m` .
therefore `I = 5 xx 10^-4m = 0.5 mm`