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Models agree on
- ✓The speed of light in a vacuum is denoted by **c**
- ✓The exact value is 299,792,458 m/s
- ✓It is a fundamental constant in physics
- ✓The speed is slower in media other than vacuum
- ✓Practical approximation is 3.00 × 10^8 m/s
The speed of light in a vacuum is a fundamental physical constant, denoted by c. Its exact value is 299,792,458 meters per second (m/s), as defined by the International System of Units (SI). This constant is pivotal across various domains of physics, including electromagnetism, relativity, and optics.
While the speed of light in a vacuum is fixed, it slows down when passing through different media like air, water, or glass. The extent of this reduction is quantified by the medium's refractive index. For practical calculations, the speed of light is often approximated as 3.00 × 10^8 m/s.
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