To calculate this we will use the light equation: λ
We have Frequency . We know that speed of light in vacuum is . Since a unit of speed of light is m/s, we can change the unit of frequency Hz to 1/s, since Hz means cycles per second (f=1/T).
So: <span> </span> <span>λ </span>⇒ λ ⇒ λ ⇒ <span>λ</span>