Question

The laser pointer emits light because electrons in the material are excited (by a battery) from their ground state to an upper excited state. When the electrons return to the ground state, they lose the excess energy in the form of 521-nm photons. What is the energy gap between the ground state and excited state in the laser material?

Answer 1

E= 3.82 ×
`10^(-19)` J

Step-by-step 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 ×
`10^(-34)` J s

c = speed of light= 3.00 ×
`10^(8)` m/s

λ = wavelength of emitted photons= 521 ×
`10^(-9)` m

E = 6.626×
`10^(-34)` × 3.00×
`10^(8)` / 521×
`10^(-9)`

E= 3.82 ×
`10^(-19)` J