Increase Photocell Illumination: Effect on Current

[bonbon22]

Homework Statement

In a photoelectric experiment, light is incident on the metal surface of a photocell.
Increasing the intensity of the illumination at the surface leads to an increase in the
[1 mark]
A work function

B minimum frequency at which electrons are emitted

C current through the photocell

D speed of the electrons

Relevant Equations

e= hf

as intensity is power per unit area
and as power is proportional to energy, then increasing intensity increases energy of the photons?no? So if energy increases so will the speed of the electrons more energy to the kinetic energy after work function?
the answer is current

 

[Alex Petrosyan]

That, my friend, is why quantum mechanics was invented!

You need to look at a very good textbook and photoelectric effect, they would find that the natural classical physics assumption, that is also assumed in your answer, is absolutely wrong. Experiments have shown that the electrons’ velocity only depends on the frequency of photons.

The higher the intensity , The more photos you have, and each photon, can only release one electron from the medium. So if you increase the intensity you get more current, not more kinetic energy of individual electrons.

However energy is conserved, so the overall energy of all released electrons, will in fact increase to cancel the extra energy and the intensity .

 

[bonbon22]

That, my friend, is why quantum mechanics was invented!

You need to look at a very good textbook and photoelectric effect, they would find that the natural classical physics assumption, that is also assumed in your answer, is absolutely wrong. Experiments have shown that the electrons’ velocity only depends on the frequency of photons.

The higher the intensity , The more photos you have, and each photon, can only release one electron from the medium. So if you increase the intensity you get more current, not more kinetic energy of individual electrons.

However energy is conserved, so the overall energy of all released electrons, will in fact increase to cancel the extra energy and the intensity .

I see as they did specifiy in the question that light was being used then increasing intensity might only mean that number of photons are increased i guess. So normally increasing the intensity of any electron magnetic radiation would increase the number and the energy of the photons ? final question.

 

[Alex Petrosyan]

Intensity, as in energy per unit area per unit time can be increased in many ways: increasing the number of photons, and increasing the energy of each photon.

The number of photons is straightforward; the energy of each - less so, it depends on the frequency of the light $\omega = 2 \pi \nu$ :

$$ E = \hbar \omega $$ or $$ E = h \nu $$