How do photons move through space, and at what speed?

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Multiple Choice

How do photons move through space, and at what speed?

Photons move through space as quanta of electromagnetic radiation. In empty space they propagate along straight-line paths at the speed of light, c, which is about 3×10^8 meters per second. They also exhibit wave-like behavior, so it’s natural to describe them in terms of waves while still acknowledging their constant, maximum speed. In a medium, their effective speed slows and their path can bend (refraction), but in vacuum the straight-line motion at the speed of light is the defining behavior.

Photons move through space as quanta of electromagnetic radiation. In empty space they propagate along straight-line paths at the speed of light, c, which is about 3×10^8 meters per second. They also exhibit wave-like behavior, so it’s natural to describe them in terms of waves while still acknowledging their constant, maximum speed. In a medium, their effective speed slows and their path can bend (refraction), but in vacuum the straight-line motion at the speed of light is the defining behavior.

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