Question

13- Which are more efficient, three-level lasers or four-level lasers?

a- Three-level lasers

b- Four-level lasers

c- They are similar in efficiency

d- Not enough information

22- In the modern atomic model, the electron is considered

a- A wave around the nuclei

b- Going around the nuclei on a circular path

c- Somewhere in a could around the nuclei

d- None of the above

23- What is the wavelength of the photon which has 3 ev of energy?

a- 41.3 nm

b- 413 nm

c- 4130 nm

d- 41300 nm

24- Which of the following is NOT a pumping mechanism for laser systems

a- Chemical reaction

b- Electric current

c- High power light source

d- Diffraction

Answer 1

13)

With a four-level scheme, you have an extra level so that the laser transition does not end in a ground state. Thus, if the bottom level gets depopulated faster than the top level in the laser transition the population inversion will be guaranteed independent of how fast or efficiently you pump the system

ans is b) 4 level laser is more efficient

22) ans is c- Somewhere in a could around the nuclei

23)

ans is option b) 413 nm

24)

ans is option d) diffraction