Answer:
E= 3.82 × [tex]10^{-19}[/tex] J
Explanation:
The energy gap between the ground state and the excited state in the laser material is equal to the energy of single 521 nm photons emitted when a single electron relaxes from the excited to ground state, i.e.
E=hf
f = c / λ so
E = h c / λ
where,
h= plank constant= 6.626 × [tex]10^{-34}[/tex] J s
c = speed of light= 3.00 × [tex]10^{8}[/tex] m/s
λ = wavelength of emitted photons= 521 × [tex]10^{-9}[/tex] m
E = 6.626×[tex]10^{-34}[/tex] × 3.00×[tex]10^{8}[/tex] / 521×[tex]10^{-9}[/tex]
E= 3.82 × [tex]10^{-19}[/tex] J