The photoelectric and photovoltaic effects | Physics | Khan Academy

When light at or above a threshold frequency shines on a metal surface, electrons are emitted from the surface. This phenomenon is called the photoelectric effect. The photoelectric effect is evidence that light is quantized—light exists as discrete packets of energy called photons. The greater the frequency of the light, the greater the energy of its photons. A closely related phenomenon is the photovoltaic effect, which is the underlying mechanism of solar cells. Sections: 00:00 - Intro 00:35 - Dependence on frequency/wavelength 03:06 - Threshold frequency/wavelength 03:54 - Dependence on intensity of light 04:56 - Failure of wave model of light 05:19 - Particle model of light (photons) 06:07 - Photon energy 07:32 - Particle nature explains photoelectric effect 08:45 - Intensity of light in particle nature 09:56 - Wave-particle duality 11:25 - Photovoltaic effect ------------------ Khan Academy is a nonprofit organization with the mission of providing a free, world-class education for anyone, anywhere. Khan Academy has been translated into dozens of languages, and 15 million people around the globe learn on Khan Academy every month. As a 501(c)(3) nonprofit organization, we would love your help! Donate here: https://www.khanacademy.org/donate?utm_source=youtube&utm_medium=desc Volunteer here: https://www.khanacademy.org/contribute?utm_source=youtube&utm_medium=desc