The wavelength of a photon of energy 5.518 × 10-26 joules is 3.6 m. The energy of the photon is: E = h * f, where h is Planck's constant and f is the frequency. The frequency of the photon is: f = c/λ, where c is the speed of light and λ is the wavelength. Therefore: E = h * f = h * c / λ. We have that E = 5.518 × 10^-26 J; h = 6.626 × 10^-34 Js; c = 2.998 × 10^8 m/s. Substitute this in the formula for the energy of the photon: 5.518 × 10^-26 J = 6.626 × 10^-34 Js * 2.998 × 10^8 m/s / λ. 5.518 × 10^-26 J = 1.986 × 10^-25 Jm / λ. λ = 1.986 × 10^-25 Jm / 5.518 × 10^-26 J. λ = 0.36 × 10 m = 3.6 m.
