A system is a group of parts that can be considered one unit. Storm systems, ecosystems, and our bodies are natural systems. Cars and houses are human-made systems. Choose an example of a system, and analyze the energy flow through the system. Describe in detail how energy enters the system, how energy changes form while in the system, and how energy leaves the system.

there are no atoms

you'd use the equation that establishes a relationship between  energy  and  wavelength, which looks like this

e=h⋅cλ, where

λ  - the wavelength of the photon; c  - the speed of light, usually given as  3⋅108m/s; h  -  planck's constant, equal to  6.626⋅10−34j s

plug the value you were given for the energy of the photon in the above equation to get the wavelength

e=h⋅cλ⇒λ=h⋅ce

λ=6.626⋅10−34js⋅3⋅108ms−1.257⋅10−24j=1.581⋅10−1m