Answer : The wavelength will be, 360.5 nm
Explanation :
Formula used :
[tex]\Delta_o=\frac{h\times c}{\lambda}[/tex]
where,
[tex]\Delta_o[/tex] = crystal field splitting energy = [tex]5.51\times 10^{-19}J[/tex]
h = Planck's constant = [tex]6.626\times 10^{-34}Js[/tex]
c = speed of light = [tex]2.998\times 10^8m/s[/tex]
[tex]\lambda[/tex] = wavelength = ?
Now put all the given values in the above formula, we get:
[tex]5.51\times 10^{-19}J=\frac{(6.626\times 10^{-34}Js)\times (2.998\times 10^8m/s)}{\lambda}[/tex]
[tex]\lambda=3.605\times 10^{-7}m=360.5\times 10^{-9}m=360.5nm[/tex]
conversion used : [tex](1nm=10^{-9}m)[/tex]
Therefore, the wavelength will be, 360.5 nm