Questions for Quantum Physics And Lasers (JC) Set 1


Which of the following scenarios about the de Broglie wavelength of an object is not possible?

  1. A 100 m sprinter has a wavelength of about 10-36 m.
  2. A stationary electron has wavelength of infinite length.
  3. An elephant with an associated wavelength equals zero.
  4. A Sumo wrestler has wavelength smaller than a child when both moves with the same speed.
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λ = h / mv
For option 3, Zero wavelength means its speed is infinite – not possible.

Answer: 3

In the production of laser, a two-level system is not preferred because

  1. there are not many elements with only two level system.
  2. too many atoms will remain in the excited state for long duration.
  3. the energy difference between the two levels is too little for photons to be emitted.
  4. population inversion will not be possible as atoms arrive in the excited level at the same rate as they leave.
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Explanation found here: https://www.miniphysics.com/how-laser-works.html
Answer: 4

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