The fundamental frequency of a sonometer wire increases by $10\text{Hz}$ if its tension is increased by$21\%$ . The fundamental frequency of the sonometer wire is $\text{Hz}$  is

  Given ,

Frequency ${\text{n}}_2=n_1+10$

Tension $T_1=100$

Tension $T_2=121$  

Frequency $n_1=?$

  $\frac{n_1}{n_2}=\sqrt{\frac{T_1}{T_2}}$

$\frac{n_1}{n_1+10}=\sqrt{\frac{100}{121}}=\frac{10}{11}$

     $11n_1=10n_1+100$

        $\therefore n_1=100\text{Hz}$