Question

Two wire A and B have equal lengths and are made of the same material, but the diameter of A is twice that of wire B. Then, for given load

• A. The extension of B will be four times that of A
• B. the extension of A and B will be equal
• C. the strain in B is four times that in A
• D. the strains in A and B will be equal

Answer 1

Answer: (A), (C)

The correct options are
A The extension of B will be four times that of A
C the strain in B is four times that in A

$\Delta l=\frac{FL}{AY}$
Thus, extension is inversely proportional to area, and also Strain=$\frac{\Delta l}{l}$ is inversely proportional to area. Thus strain in B will be 4 times that in A since diameter of B is half of A, or area of B is one-fourth of A; and similar for extensions.