The Photoelectric effect

[Ostronomos]

It seems that the photoelectric effect is not dependent on the intensity of the light but its frequency and color. Would this assumption be correct?

 

[Thief]

I have a much bigger question
but will hold it for another forum

for this thread.....yes......

take a bath in uv
take a bath in infra red
take a bath in x-ray
or cosmic
or gamma
or whatever

and see how you burn

 

[darkskies]

The rate of photoemission is proportional to the intensity of the light.

 

[Polymath257]

It seems that the photoelectric effect is not dependent on the intensity of the light but its frequency and color. Would this assumption be correct?

Color and frequency are essentially the same.

Yes, the remarkable thing about the photoelectric effect is that the intensity of the light is irrelevant to the effect. This was contrary to the classical expectations where the amplitude of the wave would decide how strong the interactions would be with that wave.

Instead, the photoelectric effect depends on the individual photons, whose energy is dependent on their frequency (not the number of them). So, the PE effect shows itself when the photons are energetic enough to give enough energy to the electrons to get out of the bonds they have with the metal. The energy of the resulting free electrons then depends on how much more energetic the photons are than that minimum.

Even if the intensity is very high, the PE effect does not show at all if the frequency is too low. And if the frequency is high enough, the PE effect shows even if the intensity is very low.

 

[Polymath257]

The rate of photoemission is proportional to the intensity of the light.

But not the energy of the emitted electrons nor whether they are emitted or not.

 

[We Never Know]

It seems that the photoelectric effect is not dependent on the intensity of the light but its frequency and color. Would this assumption be correct?

Could there be a new kind of light in the universe? Since the late 19th century, scientists have understood that, when heated, all materials emit light in a predictable spectrum of wavelengths. Research published today in Nature Scientific Reports presents a material that emits light when heated that appears to exceed the limits set by that natural law.

Advanced 'super-Planckian' material exhibits LED-like light when heated: Unconventional material emits light that exceeds limits of natural law

 

[darkskies]

But not the energy of the emitted electrons nor whether they are emitted or not.

Oh okay.

 

[exchemist]

Could there be a new kind of light in the universe? Since the late 19th century, scientists have understood that, when heated, all materials emit light in a predictable spectrum of wavelengths. Research published today in Nature Scientific Reports presents a material that emits light when heated that appears to exceed the limits set by that natural law.

Advanced 'super-Planckian' material exhibits LED-like light when heated: Unconventional material emits light that exceeds limits of natural law

What a ghastly headline. This is utterly misleading, in almost every way.

What the researcher has done is produce an optically tuned system that radiates, when heated, more than would be expected for a black body..... around one particular wavelength of the spectrum (1.7 μ, which is in the infra-red).

So it's not black body radiation at all, but more akin to the line or band emissions of quantum systems, such as electronic excited states or molecular vibrations and rotation.

It most certainly is not "a new kind of light in the universe". It is, however, very ingenious.

 

[We Never Know]

What a ghastly headline. This is utterly misleading, in almost every way.

What the researcher has done is produce an optically tuned system that radiates, when heated, more than would be expected for a black body..... around one particular wavelength of the spectrum (1.7 μ, which is in the infra-red).

So it's not black body radiation at all, but more akin to the line or band emissions of quantum systems, such as electronic excited states or molecular vibrations and rotation.

It most certainly is not "a new kind of light in the universe". It is, however, very ingenious.

Don't shoot the messenger.
That's why I post things in discussion forum's so they can be discussed and what lies in the shadows can be brought into the light.(no pun intended).

 

[exchemist]

Don't shoot the messenger.
That's why I post things in discussion forum's so they can be discussed and what lies in the shadows can be brought into the light.(no pun intended).

Don't worry, I'm not having a go at you. I've no doubt you posted this in good faith.

It just annoys me when pop-sci journos feel the need to make up preposterous headlines, in order to turn an obscure piece of physics research into something (superficially) eye-catching.