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Ch2: Planck-Einstein Energy Quantization Law:

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الكلية كلية التربية للعلوم الصرفة     القسم قسم الفيزياء     المرحلة 3
أستاذ المادة فؤاد عطية مجيد       01/11/2014 16:39:49
For a given electrode material, no photoemission exists at all below a certain frequency of the incident light. When the frequency increases, the emission begins at a certain frequency. The frequency is called threshold frequency ( nu )
of the material. The threshold frequency has to be measured in the existence of e.m.f. (electromotive force) as at such a case the photoelectrons have no kinetic energy to move from the cathode to anode. Different electrode material has
different threshold frequency.

2. The rate of electron emission is directly proportional to the intensity of the incident light.
3. Increasing the intensity of the incident light does not increase the kinetic energy of the photoelectrons.
4. There is no measurable time delay between irradiating the electrode and the emission of photoelectrons, even when the light is of very low intensity. As soon as the electrode is irradiated, photoelectrons are ejected.
5. The photoelectric current is deeply affected by the nature of the electrodes and
chemical contamination of their surface. K ? eV max
(1) In 1905, Einstein solved the photoelectric effect problem by applying the
Planck’s hypothesis. He pointed out that Planck’s quantization hypothesis
applied not only to the emission of radiation by a material object but also to its
transmission and its absorption by another material object. The light is not only
electromagnetic waves but also a quantum. All the effects of photoelectric
emission can be readily explained from the following assumptions: The
photoemission of an electron from a cathode occurs when an electron absorbs a
photon of the incident light;
(2) The photon energy is calculated by the Planck’s quantum relationship: E = h?.

المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .
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