If vibration of string is to be two times, then tension in the string must be made

Step-by-step solution

Here: Initial vibration n₁=n , final vibration n₂=2 n Initial tension T₁=T Vibration of frequency of string n= 1 2 l T m n T Hence, n₁ n₂ = T₁ T₂ or T₁ T₂ = ( n₁ n₂ )^2= ( n 2 n )^2= 1 4 or T₂=4 T₁