The drawing shows three energy levels of a laser that are involved in the lasing action. These levels are analogous to the levels in the Ne atoms of a He-Ne laser. The E2 level is a metastable level, and the E0 level is the ground state. The difference between the energy levels of the laser is shown in the drawing.

(a) What energy (in eV per electron) must an external source provide to start the lasing action?

(b) What is the wavelength of the laser light?

(c) In what region of the electromagnetic spectrum (see Figure 24.9) does the laser light lie?

Figure 24.9:

Transcribed Image Text:

AM FM Microwaves 104 108 1012 1016 1020 1024 Frequency (Hz) Ultra- Radio waves Infrared Х-гаys Gamma rays violet 104 т Wavelength (m) 10-16 10-4 10-8 10-12 4 x 1014 7.9 x 1014 Frequency (Hz) Red Violet Visible light Figure 24.9