Question

Choose the right answers

a)What is responsible for the production of x ray emission at the cutoff wavelength?
1)The last emission in a series of many emissions by the incident electron as it loses its energy.

2)The first emission in a series of many emissions by the incident electron as it loses its energy.

3)The most energetic emission in a series of many emissions by the incident electron as it loses its energy.

4)The least energetic emission in a series of many emissions by the incident electron as it loses its energy.

5)The emission by the incident electron when it loses its energy in a single emission

b)Which is true about the characteristic x-ray emission?

1)It is the radiation by electrons jumping up to higher energy levels.

2)It is the radiation by the incident electron in collisions with the atoms.

3)It is the radiation by electrons falling into lower energy levels.

c) Which is true about stimulated emission?

1) A photon is absorbed and then immediately re-emitted by an atom

2)A photon causes the de-excitation of an atom.

3) An atom emits two photons in opposite directions

4) A photon causes the excitation of an atom

5) An atom emits two photons in the same direction

d) Which is true about the pair of energy levels responsible for lasing?
1) The upper level is a long-lived state, said to be a metastable state.
2) The upper level is a short-lived state, said to be a metastable state

3) The lower level is a short-lived state, said to be a metastable state

Answer 1

)1 偽PYrduad ft rha-electimes.biard roast? 丹 e-eel (U lora-t.vd state, sa ·upper Sve꺄 level to be a metas abe atz action

Answer 2

(a) Option (1) is not correct because X-rays are highly energetic photons and its emission is continuous. Hence, it is not always tru to produce X-rays from a series of many emissions (because series of emission me be less energetic than X-rays). Option (2) is also not correct due to the above reason (because series of emission may lie anywhere in the spectrometer.) Option (3) is not correct due to the reason explained in the above line. Option (4) is also not correct due to the same reason. Option (5) is correct because production of X-rays require high energy (Energy range of X-rays lies in 100 eV to 200 keV). Hence, highly energetic electrons collide with the metal surface and electron from the bulk of the metal absorbes that energy. When this excited electron again jump to the lower energy then it emittes X-ray. Hence, when electron looses most of the energy in a single emission then it produces X-ray.