Orange light of wavelength 6000 $$ \times $$ 10^–10 m illuminates a single
slit of width 0.6 $$ \times $$ 10^–4 m. The maximum possible number of diffraction minima produced on both sides of the central maximum is ___________.

In a Young's double slit experiment 15 fringes are observed on a small portion of the screen when light of wavelength 500 nm is used. Ten fringes are observed on the same section of the screen when another light source of wavelength $$\lambda $$ is used. Then the value of $$\lambda $$ is (in nm) __________.