<P> Electromagnetic waves are typically described by any of the following three physical properties : the frequency f , wavelength λ , or photon energy E. Frequencies observed in astronomy range from 7023239999999999999 ♠ 2.4 × 10 Hz ( 1 GeV gamma rays ) down to the local plasma frequency of the ionized interstellar medium ( ~ 1 kHz ) . Wavelength is inversely proportional to the wave frequency , so gamma rays have very short wavelengths that are fractions of the size of atoms , whereas wavelengths on the opposite end of the spectrum can be as long as the universe . Photon energy is directly proportional to the wave frequency , so gamma ray photons have the highest energy ( around a billion electron volts ) , while radio wave photons have very low energy ( around a femtoelectronvolt ) . These relations are illustrated by the following equations : </P>
what is the wavelength of the electromagnetic wave
from 7023239999999999999 ♠ 2.4 × 10 Hz ( 1 GeV gamma rays ) down to the local plasma frequency of the ionized interstellar medium ( ~ 1 kHz )