Question

Two similar wires under the same load yield elongation of 0.1 mm and 0.05 mm respectively. If the area of cross- section of the first wire is then the area of cross section of the second wire is

• A.
• B.
• C. $10 \mathrm {~mm} ^ { 2 }$
• D. $12 \mathrm {~mm} ^ { 2 }$

Answer 1

Answer: (B)

Answer 2

$l = \frac { F L } { A Y } \therefore l \propto \frac { 1 } { A }$ (F,L and Y are constant)

$\frac { A _ { 2 } } { A _ { 1 } } = \frac { l _ { 1 } } { l _ { 2 } } \Rightarrow A _ { 2 } = A _ { 1 } \left( \frac { 0.1 } { 0.05 } \right)$=