Answer:
<em>By showing that changing the frequency of light causes the emission of faster electrons.
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Explanation:
<em>The photoelectric effect happens when light strikes a metal surface causing the emission of electrons from it (photoelectrons).
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<em>If you increase the intensity of the light you get, as acresult, more electrons emitted but their kinetic energy does not increase.
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<em>If you increase the frequency of the incident light the number of photoelectrons emitted does not increase while the velocity, and so their kinetic energy, increases...the emitted electrons are more...energetic!
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<em>This can be explained considering the incident light as a shower of particle-like packets of energy (photons); if you increase the intensity you simply increase the number of packets (all with the same energy) hitting the metal; these can be used by a lot of electrons to escape.
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<em>On the other hand if you increase the frequency the number of packets remains the same (emitting fewer electrons perhaps) but the energy carried by each of them increases.
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<em>Each packet carries an energy directly proportional to the frequency.</em>
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