[alancalverd]

we see a smooth increase in frequency of the emitted radiation

i.e the emitted spectrum is not generated by a quantum process, which would imply a discontinuous spectrum.

The photocell however will only react when a specific frequency is reached, indicating quantisation.

So use a thermocouple detector instead.

[hamdani yusuf (OP)]

The question here is "where does quantisation of the energy  of emr come from". If you accept that it is possible to generate emr of any arbitrary frequency, then it is clear that the energy is not necessarily quantised and the answer is that in many but not all cases it is generated by a quantum process.

The formula is E=n.h.f
Here, n is an integer. While f can have arbitrary value. In black body radiation spectrum, f is continuous.

[hamdani yusuf (OP)]

Line Broadening

An explanation of why a four level laser can be more efficient than a three-level laser, by students Manish Trivedi and Emma Wroe from the Department of Medical Physics and Bioengineering at University College London.

Line Broadening

An explanation of line broadening in the context of laser physics, by students Konstantina Violaki and Lebina Shrestha from the Department of Medical Physics and Bioengineering at University College London.

Line broadening, including from Doppler effect, shows that describing light as point particles is not feasible. The math from Fourier transform should be obvious.
Description of light as electromagnetic wave caused by motions of electrically charged particles can meet most constraints set by known experimental results.

[hamdani yusuf (OP)]

I found a question in quora. Why are the absorption and emission spectrums the same?

Calling it absorption spectrum is a bit misleading, missing the full picture and causes misinterpretations. Where do the energy from the absorbed lights go?

See this image. It looks more like scattering spectrum. The unscattered frequencies are received by the sensor on the right side at full intensity. While scattered frequencies look darker there because the energy at those frequencies are scattered to different direction.

https://www.quora.com/Why-are-the-absorption-and-emission-spectrums-the-same/answer/Hamdani-Yusuf?ch=10&oid=1477743812950057&share=e48f96ac&srid=uvWW4&target_type=answer

[alancalverd]

Because what goes up must come down, and the transitions of bound electrons are quantised.

[alancalverd]

describing light as point particles is not feasible.

...unless you are counting photons.

[hamdani yusuf (OP)]

describing light as point particles is not feasible.

...unless you are counting photons.

How do you count photons?

[hamdani yusuf (OP)]

Here's a picture of undulator.

The arrangement of magnets can be arbitrarily chosen to produce any shape of spectrum, which is continuous instead of monochromatic. One photon worth of radiation energy must contain a range of frequency, as required by Fourier transform. 

[alancalverd]

How do you count photons?

At low energies, with a photomultiplier. At high-ish (keV to MeV) energies, with a semiconductor detector. At higher energies, with an energy-specific scintillator.

[alancalverd]

One photon worth of radiation energy must contain a range of frequency, as required by Fourier transform. 

The it wouldn't be a photon. The particle model only allows one frequency per photon.

[hamdani yusuf (OP)]

One photon worth of radiation energy must contain a range of frequency, as required by Fourier transform.

The it wouldn't be a photon. The particle model only allows one frequency per photon.

Then the model is inaccurate or incomplete.

[hamdani yusuf (OP)]

How do you count photons?

At low energies, with a photomultiplier. At high-ish (keV to MeV) energies, with a semiconductor detector. At higher energies, with an energy-specific scintillator.

Can it detect photon in radio frequencies?
They detect transfer of electron, which can be initiated by various causes, such as temperature, electromagnetic interference, cosmic rays.

[alancalverd]

Then the model is inaccurate or incomplete.

It is obviously incomplete, but apparently very accurate.

[alancalverd]

Can it detect photon in radio frequencies?

Most radio frequencies are generated as a continuum but the RF signals from nuclear magnetic resonance and electron spin resonance relaxation are inherently quantised.

[hamdani yusuf (OP)]

Can it detect photon in radio frequencies?

Most radio frequencies are generated as a continuum but the RF signals from nuclear magnetic resonance and electron spin resonance relaxation are inherently quantised.

What kind of quantization is it?
Is the frequency quantized?
Is the intensity quantized?
Is the pulse width or duration quantized?
Is the radiated energy quantized?

[alancalverd]

All of the above.

[hamdani yusuf (OP)]

All of the above.

What's the minimum non-zero value of these quantities?
frequency
intensity
pulse width or duration
radiated energy
?

[alancalverd]

Zero plus a bit.

The gyromagnetic ratio of a proton is about 42 MHz/T, so with a low enough magnetic field the spin flip energy can in principle be anything you want. In practice we rarely use less than 0.1T but imaging systems have been constructed to use the earth's magnetic field (around 50 μT).

[hamdani yusuf (OP)]

Zero plus a bit.

Can I reduce it to a half bit? Why or why not?

[alancalverd]

Depends how big your bit is! The singularity where all your parameters are zero occurs exactly when the charge carrier is not moving.