To calculate the energy of the photon emitted, we use the formula that relates the energy of a photon to its wavelength:
\[
E = \frac{hc}{\lambda}
\]
Where:
- \( E \) is the energy of the photon,
- \( h = 6.626 \times 10^{-34} \, \text{J·s} \) is Planck's constant,
- \( c = 3.0 \times 10^8 \, \text{m/s} \) is the speed of light,
- \( \lambda = 656.3 \times 10^{-9} \, \text{m} \) is the wavelength of the light.
Substituting the known values:
\[
E = \frac{6.626 \times 10^{-34} \times 3.0 \times 10^8}{656.3 \times 10^{-9}}
\]
\[
E = \frac{1.9878 \times 10^{-25}}{656.3 \times 10^{-9}} = 3.02 \times 10^{-19} \, \text{J}
\]
Thus, the energy of the photon emitted during the transition is \( 3.02 \times 10^{-19} \, \text{J} \).