We know
[tex]\boxed{\sf \lambda=\dfrac{C}{V}}[/tex]
[tex]\\ \sf\longmapsto \lambda=\dfrac{3\times 10^8ms^{-1}}{4.75\times 10^{12}s^{-1}}[/tex]
[tex]\\ \sf\longmapsto \lambda=0.631\times 10^{-4}m[/tex]
[tex]\\ \sf\longmapsto \lambda=6.31\times 10^{-5}m[/tex]
