What is Photoelectric effect?

zxteh

有谁可以助我explain about it...---Photoelectric effect n Einstein Equation?
What is Work function n how to know the relationship between work function n the threshold frequency?W=hfo
and E=W+(1/2)mv^2 What is the meaning.....?
Why Einstein say different frequency can have the radiotion but not different intensity....why increses the frequecy can cause the photoelectric effect but increases the intensity only increase the number of moles of electron....?
可以助我explain..... ?
Thanks....?

distantstar

this is the knowledge I learnt last year, I wonder if I can remember all of it, but i will try my best to explain it to you.

Photoelectric effect - Radiation can be regarded of comprising particles with energy - photons. When light is radiated towards the surface of a metal (or watever substances possible for photo effect), electrons of the metal atoms, if obtain sufficient energy from the photons, are able to escape from the metal atoms and become free electrons or photoelectrons.However, if the energy of the photon, which is related to the frequecy of the radiation ( E = hf ）， is not high enough, no photoelectrons will be ever produced。Therefore, here comes the concept of work function, which can be defined as the minimum energy required to produce a photoelectron from a metal surface.In such a case, the values of work function different metal vary from one another.

Einstein equation is basically established based on the concept of the conservation of energy.
Energy of photon supplied=Work function+kinetic energy obtained by photoelectrons
or
    hf = W + 1/2 mv^2
hf is the energy of the photon
W is the work funtion of the metal
1/2 mv^2 is the maximum kinetic energy otained by the photoelectrons
(its the maximum kinetic energy in the idealised case. But, in real life, some photoelectrons, upon liberated from metal surface, may lose some of its kinetic energy.)
This is the Einstein Equation for photoelectric effect.

We should note that if radiation with high intensity but with frequency lower than the threshold frequency of the related metal may NOT cause photoelectrics effect because each photon of the radiation possesses no energy (which only related to the frequency of the radiation)greater than the work function. Therehold frequency, fo, is the minimum frequency of the radiation required to produce photoelectric effect. Hence, work function, W = hfo。

Radiation with higher intensity indicates that there are more photons hit the suface of the metal per second. If the frquency of the radiation is able to produce photoelectrics effect, two radiation with that same frequency but different intensity, the one with higher intensity may produce more photoelectrons per second because there are more photons that land on the metal surface per second.

Hope that my explanation can help you a little bit more.

zxteh

Thank...4 ur explanation....

zxteh

what is different between phooelectric effect n wave particle duality.....?
why wave particle duality always use the equation p=hf/c.....?
what n why wave can have the particle properties.....?
what n why particle can have the wave properties....?
how can the wave change with particle....?
why n what de Broglie make the assumption to prove his theory is true...?
how can the equation make with their assupmtion to relate the equation with the special relativity with the quantum theory.....?

zxteh

can everybody help me to explain detail for me....?
Thank.............?

photoelectric effect shows that light is particle......but classically light was treated as wave.so de broglie found that the particle can have wave properties and wave can have particle properties. like the electron pass through single slit can show the difraction pattern....and the classically light wave show particle properties in compton effect....

中庸

so if light is a particle...then it should have momentum....so E=pc.....then given by planck E=hf...then pc=hf. E=pc is given by speacial relativity.....E=hf is given by the quantization of light energy in quantum theory....