Find the value of $k$ for which $f(x)=\left\{\begin{array}{c} \frac{\sin 2 \mathrm{x}}{5 \mathrm{x}}, \text { when } \mathrm{x} \neq 0 \\ \lambda, \text { when } \mathrm{x}=0 \end{array} \text { is continuous at } \mathrm{x}=0\right.$