The energy of a photon is equal to the product of planck's constant,h and speed of light,c over the wavelength,y. Hence, e=h*[tex] \frac{c}{y} [/tex]. h is equal to 6.6261*10^-34 Js, c is equal to 3*10^8 m/s and y= 12.7 cm or 0.127 m. Substituting, energy is equal to 1.5652*10^-24 Joules.
