In laser production the state in which more atoms are in the upper state than in the lower one is called_____________?

Related Mcqs:

The radiations emitted form hydrogen filled discharge tube show____________?

A. band spectrum B. line spectrum C. continuous spectrum D. absorption spectrum...

When we excite some atoms by heat collision or electrical discharge they will________________?

A. radiate electromagnetic energy with a continuous distribution of wavelength B. absorb particular wavelengths when white light is incident on them C. radiate electromagnetic energy of discrete characteristic wavelength D. emit either invisible or visible light...

In obtaining an X-ray photograph of our hand we use the principle of______________?

A. photo electric effect B. ionization C. shadow photograph D. any of above...

X-rays are diffracted by a crystal but not by a diffraction grating because_____________?

A. The ions in a crystal are well arranged B. The lines in a diffraction grating cannot reflect X-rays. C. The penetration power of X-rays is high in a diffraction grating D. The wavelengths of X-rays are of the same order of magnitude as the separation between atoms in a crystal...

Electron cannot exist in the nucleus it is confirmed by observing that______________?

A. It does emit radiation B. Its size as compare to proton and neutron is very small C. No antiparticle of electron is present D. The velocity of electron must be very high according to uncertainty principle...