Alex McColgan
speaker
29,301 appearances
104 recordings
1 series
first heard Nov 2024
last heard 6d ago
Alex McColgan’s voice in public audio — every appearance, attributed to the second.
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recordings per month · last 12 monthsRecordings per month over the last 12 months — 68 in all, peaking in Aug 2026 with 11.
Appearances
Let's fast forward another 100 years to 1905.
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Scientists around this time had become puzzled by something known as the photoelectric effect.
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It turned out that when you shone a light on a metal surface, electron-like particles were coming off it.
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This was deduced to be because electrons in the metal were getting knocked off it by the increased energy the light was imparting.
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Imagine it like a fruit on a tree.
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If you pull the fruit off the tree, you need to use a certain amount of energy.
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Once the energy is greater than the strength of the fruit's connection to the branch, the fruit pops off.
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This was happening with the light and the electrons.
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Once the light hit an electron and gave it enough energy to pass the threshold, it broke free from the metal.
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However, what surprised scientists was that if you increased the intensity of the light, they had expected the electrons to be knocked away faster.
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If you pulled the fruit off the tree harder, it would come off faster.
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More energy equals more departing kinetic energy.
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However, this did not appear to be the case.
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Instead, increasing the frequency of the light increased the velocity of the departing electrons.
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The intensity of the light didn't affect the departing electron's velocity at all, but did affect the quantity of electrons being emitted.
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It was a bit of a puzzler.
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Albert Einstein was the man who solved the puzzle.
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He deduced that light must be travelling in little packets of energy, so sending more of them, increasing the frequency, was the only way to increase the energy going to the electrons.
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He called these packets photons, and later earned a Nobel Prize for his work.
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Light, it seemed, was more like a particle again.
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Showing 2061–2080 of 29,301 · page 104 of 1466
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