Question

Four identical rods are stretched by same force. Maximum extension is produced in

• A. $L = 10 \mathrm {~cm} , D = 1 \mathrm {~mm}$
• B. $L = 100 \mathrm {~cm} , D = 2 \mathrm {~mm}$
• C. $L = 200 \mathrm {~cm} , D = 3 \mathrm {~mm}$
• D. $L = 300 \mathrm {~cm} , D = 4 \mathrm {~mm}$

Answer 1

Answer: (B)

$L = 100 \mathrm {~cm} , D = 2 \mathrm {~mm}$

Answer 2

$l = \frac { F L } { \pi r ^ { 2 } Y }$∴ $l \propto \frac { L } { r ^ { 2 } }$

Ratio of $\frac { L } { r ^ { 2 } }$ is maximum for wire in option (2).