Photoelectric effect+frequencies

[hurricane89]

does anyone know what the minimum frequency actually is that the light needs to be in order for photons to be emmited? also, is there a point where if the frequencies too high, does THAT = no electron emmision? that is all!

 

[Bob S]

I think that there are some photocathodes that work up to about 650 nanometers wavelength for photoelectrons to be emitted. Using 300 meters = 1 MHz as a conversion, 650 nanometers converts to 4.6 x 10¹⁴ Hz.
The photoelectric effect is important up to photon energies of about 100 keV, the binding energy of k-shell (1S) electrons in the heaviest nuclei. Using 1 eV= 1240 nm = 2.4 x 10¹⁴ Hz, 100 kHz corresponds to 2.4 x 10¹⁹ Hz.

 

[hurricane89]

oh so there's a bunch of electricity involved huh. are hertz how many times the photon zigzags per second?

 

[ZapperZ]

does anyone know what the minimum frequency actually is that the light needs to be in order for photons to be emmited? also, is there a point where if the frequencies too high, does THAT = no electron emmision? that is all!

oh so there's a bunch of electricity involved huh. are hertz how many times the photon zigzags per second?

There is a problem in the very basic understanding of the photoelectric effect here. Maybe you should start with the basic Einstein's photoelectric effect equation, and then see if there is still something you don't understand.

http://galileo.phys.virginia.edu/classes/252/photoelectric_effect.html

In particular, pay attention to what is meant by the work function that is material dependent.

Zz.

 

[hurricane89]

There is a problem in the very basic understanding of the photoelectric effect here. Maybe you should start with the basic Einstein's photoelectric effect equation, and then see if there is still something you don't understand.

http://galileo.phys.virginia.edu/classes/252/photoelectric_effect.html

In particular, pay attention to what is meant by the work function that is material dependent.

Zz.

"(he called the transmitter spark A, the receiver B): "I occasionally enclosed the spark B in a dark case so as to more easily make the observations; and in so doing I observed that the maximum spark-length became decidedly smaller in the case than it was before. On removing in succession the various parts of the case, it was seen that the only portion of it which exercised this prejudicial effect was that which screened the spark B from the spark A. The partition on that side exhibited this effect, not only when it was in the immediate neighbourhood of the spark B, but also when it was interposed at greater distances from B between A and B. A phenomenon so remarkable called for closer investigation."

i don't understand this part at all. why is it that when there's less light, this = less electrons? less light would mean that less electrons would be knocked off. which would mean that the charge would maintain itself in the dark. this is backwards and doesn't make sense. why is it that the electric charge decreases i nthe dark box, when light, removes electrons? ? feel free to jump in and answer this if you know the answer i don't get it AT ALL!