Equations · equation
Refractive Index
Waves & Optics · 1678
- Equation
- n = c / v
- Field
- Waves & Optics
- Symbols
- n refractive index of a medium · c speed of light in vacuum · v speed of light in the medium
- Year
- 1678
Significance
Light slows in matter — by a third in glass, a quarter in water, a factor of 2.4 in diamond — and the ratio is the refractive index. Snell's law is the consequence: the wavefront bends where its speed changes. It is why a lens focuses, a prism disperses, a fibre guides, and a diamond sparkles; Huygens explained it with wavefronts in 1678.
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