Explanation: \(\text{Hints: } \frac{T_1}{T_2} = \sqrt{\frac{L_1}{L_2}}\) \(\text{Solve: } \frac{T_1}{T_2} = \sqrt{\frac{L_1}{L_2}} \implies L_2 = \frac{T_2^2}{T_1^2} \cdot L_1\) \(\therefore L_2 = (1.41T_1)^2 \cdot \frac{L_1}{T_1^2} \implies L_2 = 2L_1\) \(\text{Ans. (B)}\) \(\text{ব্যাখ্যা: } T \propto \sqrt{L}, \, \text{অতএব } \frac{T_1}{T_2} = \sqrt{\frac{L_1}{L_2}}.\)