(a) $\beta = \frac{\lambda D}{d} \Rightarrow \left( 0.06 \times 10^{- 2} \right) = \frac{\lambda \times 1}{1 \times 10^{- 3}} \Rightarrow \lambda = 6000\mathring{\mathrm{A}}$
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.