\(d \sin \theta=\lambda\)
\( \Rightarrow d = \frac{\lambda }{{\sin \theta }} = \) \(\frac{{5000 \times {{10}^{ - 8}}{\text{cm}}}}{{\sin {{30}^o}}}\)
\( = \frac{{5000 \times {{10}^{ - 8}}{\text{cm}}}}{{1/2}}\) \( = 10 \times {10^{ - 5}}{\text{cm}}\)