Energy levels transitions of an electron?
If I remember correctly, you can use the equation:

$$E = \frac{hc}{\lambda}$$

and 

$$\nu = \frac{c}{\lambda}$$

to solve for the frequency, wavelength, or energy of the photon. Note that $E$ is energy, $h$ is Planck's constant, $c$ is the speed of light, $\lambda$ is the wavelength, and $\nu$ is frequency.

The energy, (actually 11.97eV not 11.2eV)converted into joules (2.719 $*10^{-18}$ J) and then put into the first equation:

1.918 $×10^{-18}$ J = $\frac{6.626× 10^{-34} × 2.998 × 10^7 m×J}{\lambda}$

then lambda can be solved for:

$\lambda$ = $\frac{6.626× 10^{-34} × 2.998 × 10^7 m×J}{1.918×10^{-18} J}$

$\lambda$ = $1.036×10^{-7} m $

= 103.6 nanometers.

This solves for your wavelength like you asked for.