ENGINEERING PHYSICS

Life time of electron in ground state of an atom in seconds

• 0

• equal to half life period

• 1

• Infinite

Population inversion for Lasing action means

• More electrons in ground state than excited state

• More electrons in any excited state than ground state

• More electrons in 1st excited than ground state

• More electrons in metastable state than ground state

According to Einstein at equilibrium

• Rate of absorption of radiation is equal to rate of stimulated emission

• Rate of spontaneous emission is equal to rate of stimulated emission

• Rate of absorption of radiation is equal to rate of spontaneous emission

• Rate of stimulated emission is constant

If optical resonator is not formed

• No output in laser would be there

• Output would be there but would stop very soon

• Intensity can't grow

• No laser would be produced at all

Find the difference between two energy levels of Neon if the transition levels gives a photon of wl 6328 Angstrom.

• 3.14 X 10-19 J

• 3.14 J

• 3.14 x 10-12 J

• 1.96 J

In Ruby laser optical pumping is done through

• external green light

• electric discharge

• by heating the system

• external red light

In He-Ne laser active energy levels for transitions are provided by

• Ne atoms

• He atoms

• Both He and Ne

• Co2 atoms

We get continuous laser from

• Ruby

• Diode

• He-Ne

• Co2

We get pulse laser from

• Ruby rod

• He, Ne laser 10:1 ratio

• CO2 laser

• Diode laser

In Physics lab the laser we use is

• He-Ne laser

• Ruby laser

• Diode laser

• Co2 laser