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Physics

The Photoelectric Effect as Evidence for Light Quanta

Quick fact

The photoelectric effect is so sensitive to frequency that even a very dim violet light can eject electrons from a metal, while an extremely intense red light cannot—revealing that light's energy is delivered in fixed packets.

Why this is interesting

When you shine light on a metal, sometimes electrons fly off—but only if the light is blue enough, no matter how bright a red light is. Why would a dim blue light work when a blazing red light fails?

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The Photoelectric Effect as Evidence for Light Quanta

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