A copper wire was subjected to a tensile stress of 7.7 x 10^7 x 10 Nm−². Calculate strain of the wire. [young modules = 1.1 x 10¹¹ Nm−²]

A. 2. 0 x 10^-5
B. 7.0 x 10^-3
C. 7.0 x 10^-4
D. 2.2 x 10^-4

Correct Answer:

Option C – 7.0 x 10^-4

Explanation

Young modules = Tensile stress/Tensile strain

= 1.1×10^11=7.7×10^7/Tensile Strain

∴ Tensile strain = 7.7×10^7/1.1×10^11

= 7.0×10^7−11 = 7.0×10^−4