An electron undergoes a transition from an initial (ni) to a final (nf ) energy state. The energies of the ni and nf energy states are −2.179×10−18J and −8.720×10−20 J, respectively.

Calculate the wavelength (λ) of the light in nanometers (nm) corresponding to the energy change (ΔE) value of this transition. You can use the following values for your calculations:

Planck′s constant (h) = 6.626×10−34 J⋅s
speed of light (c) = 2.998×108 m/s
1 m = 109 nm

Question

An electron undergoes a transition from an initial (ni) to a final (nf ) energy state. The energies of the ni and nf  energy states are −2.179×10−18J and −8.720×10−20 J, respectively.

Calculate the wavelength (λ) of the light in nanometers (nm) corresponding to the energy change (ΔE) value of this transition. You can use the following values for your calculations:

Planck′s constant (h) = 6.626×10−34 J⋅s
speed of light (c) = 2.998×108 m/s
1 m = 109 nm

anonymous · Answer

$$\Delta E=(n_f-n_i)$$

anonymous · Answer

so you should be able to use 

$$\lambda = \frac{hc}{\Delta E}$$

anonymous · Answer

let me know if that looks familiar it's been a while since i have done this type of problem