Calculate the change in energy of an atom that emits a photon of wavelength 2.21 meters. (Planck’s constant is 6.626 x 10-34 joule seconds, the speed of light is 2.998 x 108 m/s)

Answer 1

h f
where h = 6.626 * 10^-34
f = 1/T = c/lambda = 2.998*10^8/2.21

so
E = 6.626*10^-34 * 2.998*10^8/2.21 Joules

Answer 2

dont