solution:
You need to find the frequency, and they have already given you the wavelength. And since you already know the speed of light, you can use formula (2) to answer this problem. Remember to convert the nano meters to meters because the speed of light is in meters. [tex](1 nm = 1.0 x 10^{-9} m)[/tex]
[tex]v=c\lambda \\
v= (3.00 \times 10^8 m/s)/(6.9\times 10^-7 m) \\
v = 4.35 \times 10^{14} s^{-1}[/tex]
