Introduction to the Photoelectric Effect | A-level Physics | OCR, AQA, Edexcel

[@anisabanu1069]

Thank you for saving my life with this video!! 🙏🏻🙏🏻

[@carolnglinjoo4059]

Hi. Thank you for reminding me.

[@manaltazulislam9238]

AMAZING😍

[@darkpastbrightfuture.832]

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[@abdulrahmanrahim-x9r]

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[@ryanc.3997]

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[@hasemkcs7414]

Nice

[@erinelagoz7666]

No need for school. TY

[@SM-hx9ic]

may I ask a question? in the previous videos you said that photoelectric effect supports the particle-like property of light, but in this videos, the photoelectric effect only seems to support EM-wave property. How does photoelectric effect supports the particle-like property of the light?

[@sartajpurewal5429]

Because light is both a wave and a particle

[@heinzarniaung2915]

The experiment goes like this right: 1. We make the zinc plate and the gold leaf negatively charged. This means there are more electrons throughout the zinc plate and gold leaf. 2. This causes the gold leaf and metal plate to repel each other. 3. When we shine a specific form of light on the plate, the gold leaf drops down. Why? Because the light hitting the plate gives the electrons in the plate enough energy to become free photoelectrons. This reduces the overall charge and hence the repulsion between the zinc and the gold leaf. 4. If we shine a bright visible light on the metal, the electrons SHOULD gain enough energy to become free photoelectrons. (Bright light = light wave with high amplitude = more energy.) But this does not happen no matter how bright the light is, so light can't be a wave. 5. If we shine an ultraviolet light (higher frequency), the gold plate drops down. So this means light with a higher frequency will cause the electrons to gain enough energy. This behavior can't be explained when light is a wave only when it is a particle.

[@James-gf8es]

This is only evidence, not proof, moreover mathematics is needed to really make this clear, but 1) there is a minimal frequency of radiation required to emit an electron. This quantal observation is hard to explain with a non-quantized theory of light. A particle or quantized theory of light also provides a more descriptive explanation for observation 2) The observation that the frequency of the radiation increases the max speed of emitted electrons. This hints that the frequency of light might be related to the speed or energy of light particles (photons). The particle perspective is further corroborated by the observation that light amplitude increases the number of electrons emitted i.e. more photons implies more electrons emitted. Try to explain these observations with only the wave theory, and you will see that it is hard to form a descriptive model of these observations. Why should amplitude not increase the KE of emitted electrons? Why should frequency not increase the number of electrons released after the frequency threshold is reached?