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Published byAbigail Clarke Modified over 2 years ago

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Photoelectric Effect

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Absorption Charges can absorb electromagnetic waves. Can cause charge to accelerateCan cause charge to accelerate Moving chargeabsorbed photon

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Ejected Electrons Electromagnetic energy could eject electrons from the surface. Accelerate with voltageAccelerate with voltage Measure currentMeasure current Classical expectation is that the current varies with intensity. May also vary with frequency.May also vary with frequency. V e I

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Stopping Potential As the voltage is decreased the photocurrent decreases. Matches classical viewMatches classical view The voltage can be reversed and some current flows. Stopping point independent of intensityStopping point independent of intensity Characteristic of metalCharacteristic of metal V e I

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Atomic View A photon can eject an electron from an atom. Photon absorbed Electron released Energy within the atom is quantized. Minimum energy needed for interaction Einstein’s photoelectric equation e Z

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Work Function The minimum energy is the work function of the metal. Below a certain frequency no current can flow. f 0 = /hf 0 = /h Work functions for some metals: Na: 2.28 eV Co: 3.90 eV Al: 4.08 eV Pb: 4.14 eV Zn: 4.31 eV Fe: 4.50 eV Cu: 4.70 eV Ag: 4.73 eV Pt: 6.35 eV

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Photocell The photoelectric effect is commonly used to measure light. Camera light meterCamera light meter It can also generate electricity. Photovoltaic cellPhotovoltaic cell next

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