Frequency =6.75×10^14s^{-1}
[tex]\\ \sf\longmapsto \lambda=\dfrac{c}{v}[/tex]
[tex]\\ \sf\longmapsto \lambda=\dfrac{3\times 10^8m/s}{6.75\times 10^{14}s^{-1}}[/tex]
[tex]\\ \sf\longmapsto \lambda=0.444\times 10^{-6}m[/tex]
[tex]\\ \sf\longmapsto \lambda=0.4\mu m[/tex]
