IIT JEE , AIEEE Forum - Physics , Modern Physics

johncena

we know that maximum speed with which an information can be transferred or minimum time taken for information to processed is that of ultimate speed.

Now in postulates of photo electic effect it is given that when a photon with minimum frequency(threshold frequency) strikes an electron it immideatly comes out i.e there will be no time lag.

is it not a contradiction? yes or no and why?

aditya_arora04

Sorry, could not understand your question !!!!

Please be more clear

iitkgp_bipin

Attempts have been made to determine how long it takes for the electrons to absorb enough energy from the light to escape from the plate. No detectable time lag has been found. The electrons absorb the energy from the light beam nearly instantaneously. This result is independent of the intensity and frequency of the incident light (so long as the frequency is high enough to cause photoemission, of course).

The photon interpretation of the photoelectric effect predicts that there will be no appreciable time lag between light striking the surface of a metal and the start of photoemission. This is in complete agreement with the experimental results. Each electron absorbs the energy it needs to escape in a finite but very small interval of time. We can make a rough guess at the value of the amount of time the absorption occurs in, by setting it equal to the length of time it would take for a photon (traveling at the speed of light) to cross an electron. The size of an electron is not a well-determined quantity, but is of the order of 10^-14 m. Therefore, the absorption time is, roughly

10^-14/(3x10⁸) = 10^-22/3 sec

There is no way in which such a short time interval could be measured.

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