\(\theta_1=sin^{-1}\frac{m \lambda_1}{a}=sin^{-1}\frac{2(400*10^{-7})cm}{1/5000cm}=23.58^0\)

\(\theta_2=sin^{-1}\frac{m \lambda_2}{a}=sin^{-1}\frac{2(600*10^{-7})cm}{1/5000cm}=36.87^0\)

\(\Delta \theta=\theta_2 - \theta_1=13.292^0\)