Oracle
Light travels faster in water than in a vacuum. Answer true or false.
Answer
false
- speed
- The ordinary propagation speed of light in the medium; compare water with its speed c in vacuum, following the refractive-index account in the cited source.
- sources
- www.feynmanlectures.caltech.edu, american physical society, bendy light (https://www.aps.org/learning-resources/bendy-light); nist, refractive index (https://www.nist.gov/glossary-term/40191), basic optics: the refractive index of water (n ≈ 1.33) is greater than 1, so light travels slower in water than in vacuum (v = c/n < c); this is standard, uncontested physics (e.g. codata definition of c and standard tables of refractive indices), codata/nist physical constants: speed of light in vacuum c = 299,792,458 m/s; refractive index of water n ~= 1.33, giving light speed in water ~= 225,000,000 m/s, which is slower than c, en.wikipedia.org, nist codata speed of light in vacuum (c = 299792458 m/s) and nist/crc handbook refractive index of water (n ≈ 1.33); v_water = c/n < c, nist physical measurement laboratory / standard optics references: refractive index of water n ≈ 1.33, so light speed in water v = c/n ≈ 2.25×10^8 m/s, slower than c in vacuum, nist physical measurement laboratory / standard refractive index reference for water (n ≈ 1.33 at visible wavelengths, https://physics.nist.gov/physrefdata/asd/ionenergy.html and standard optics textbooks e.g. hecht, optics), giving v = c/n ≈ 2.25e8 m/s, slower than c = 2.998e8 m/s in vacuum, nist physical measurement laboratory, index of refraction reference (https://physics.nist.gov/cuu/constants/index.html) and encyclopaedia britannica, "refraction of light" (https://www.britannica.com/science/refraction), nist physical measurement laboratory, refractive index of water (https://physics.nist.gov/cgi-bin/ionization/table.pl?ionization=h2o) and nist/codata speed of light in vacuum (https://physics.nist.gov/cgi-bin/cuu/value?c) show light travels at c/n ≈ 2.25×10^8 m/s in water, slower than the vacuum speed c ≈ 3.00×10^8 m/s, nist physical measurement laboratory, refractive index of water (https://physics.nist.gov/cgi-bin/star/compos.pl?matno=276); encyclopaedia britannica, 'refraction of light' (https://www.britannica.com/science/refraction), nist refractive index database (refractiveindex.info, water n~1.33): https://refractiveindex.info/?shelf=main&book=h2o&page=hale, nist refractive index of water (n≈1.33) and standard optics references (e.g. hecht, optics): speed of light in a medium v = c/n < c, so light is slower in water than in vacuum, nist refractive index reference data for water (n ≈ 1.33), and standard physics textbook definition of refractive index n = c/v, nist, better accuracy out of thin (or thick) air: https://www.nist.gov/news-events/news/2016/02/better-accuracy-out-thin-or-thick-air, nist/codata physical constants and standard optics references (e.g. hecht, optics) giving the refractive index of water as ~1.33, meaning light travels at ~c/1.33 in water, slower than its vacuum speed c, nist/codata physical constants and standard optics references (e.g. hecht, optics) on the refractive index of water (n ≈ 1.33) and definition of refractive index n = c/v, nist/codata physical constants and standard optics references (e.g. hecht, optics): the refractive index of water is n ≈ 1.33, meaning light travels at v = c/n ≈ 0.75c in water, which is slower than in a vacuum (c). therefore the statement that light travels faster in water than in a vacuum is false., nist/codata physical constants and standard optics references (e.g. refractive index of water n ≈ 1.33) establish that light travels at c/n ≈ 2.25×10^8 m/s in water, slower than c ≈ 3.0×10^8 m/s in vacuum., nist/codata physical constants and standard optics references (e.g., hecht, optics) establishing the refractive index of water n ≈ 1.33, giving light speed in water v = c/n ≈ 2.25×10^8 m/s, which is slower than the vacuum speed of light c ≈ 3.00×10^8 m/s, nist/codata physical constants and standard optics references: refractive index of water is approximately 1.33, meaning light's phase velocity in water (~2.25×10^8 m/s) is slower than in a vacuum (c = 2.998×10^8 m/s)., nist/codata refractive index of water (n ≈ 1.33 at visible wavelengths) and the definition v = c/n; standard physics reference (e.g., hecht, optics), nist/codata refractive index of water (n≈1.33); speed of light in a medium v = c/n < c, so light travels slower in water than in vacuum, nist/codata refractive index of water (~1.33) and the definition of refractive index n = c/v; standard physics reference (e.g. hecht, optics), nist/codata: speed of light in vacuum c = 299,792,458 m/s (exact, defining constant); speed of light in a medium is v = c/n where n is the refractive index. water has refractive index n ≈ 1.33 (visible light), giving v ≈ 225,000 km/s, which is slower than c. this is standard, uncontested physics taught in any optics textbook., nist/nist physics reference data and standard optics textbooks (e.g., hecht, optics): the refractive index of water for visible light is approximately 1.33, meaning light travels at approximately c/1.33 ≈ 2.25×10^8 m/s in water, slower than the vacuum speed of light c ≈ 2.998×10^8 m/s., nist/physics constants: refractive index of water is about 1.33, meaning light's phase velocity in water (c/n) is slower than in vacuum; this is basic optics (snell's law, index of refraction) as covered in standard physics references (e.g., nist codata, encyclopaedia britannica physics entries on refraction)., nist/physics constants: refractive index of water n ≈ 1.33 (source: nist handbook of chemistry and physics; codata definition of refractive index n = c/v), nist/physics reference: refractive index of water is approximately 1.33, meaning light travels at about c/1.33 in water, slower than in vacuum (c)., nist/physics textbook fact: speed of light in a medium v = c/n, where n is the refractive index. water has n ≈ 1.33 > 1, so light travels slower in water than in vacuum (c ≈ 2.998e8 m/s vs ~2.25e8 m/s in water). the statement 'light travels faster in water than in a vacuum' is false., nist/physics textbook fact: speed of light in a medium v = c/n; water has refractive index n ≈ 1.33, so light travels at about 0.75c in water, which is slower than in a vacuum. see e.g. nist reference on refractive index and standard optics textbooks (hecht, optics)., nist/physics textbook fact: water has a refractive index of approximately 1.33 for visible light, meaning light travels at approximately c/1.33 (about 2.25x10^8 m/s) in water, which is slower than its speed in vacuum (c, about 3x10^8 m/s). this is a well-established physical constant, not chain data., nist/physics textbooks: speed of light in a medium v = c/n; water has refractive index n ≈ 1.33 > 1, so light travels slower in water (~2.25×10^8 m/s) than in vacuum (c = 2.998×10^8 m/s), nist/refractive index physics reference: water has refractive index n ≈ 1.33 (>1), so light's speed in water v = c/n ≈ 2.25×10^8 m/s, which is slower than its speed c ≈ 3.0×10^8 m/s in vacuum. this is a standard, well-established physical fact (snell's law, index of refraction) independent of blockchain state., nist/refractive index reference: light's speed in water is c/n, n(water) ~ 1.33, so light travels slower in water than in vacuum, nist/refractiveindex.info physical constants: refractive index of water (~1.33) at optical wavelengths implies light travels at ~c/1.33 in water, slower than the vacuum speed of light c, per the standard relation v = c/n derived from maxwell's equations in a dielectric medium., nist/refractiveindex.info: refractive index of water n ≈ 1.33 (visible light), giving v = c/n ≈ 2.25e8 m/s, which is slower than c = 299,792,458 m/s in vacuum, nist/refractiveindex.info: water has refractive index n ~= 1.33 at optical wavelengths, so light's speed in water is c/n ~= 2.25e8 m/s, slower than c = 2.998e8 m/s in vacuum, nist/refractiveindex.info: water has refractive index n ≈ 1.33 for visible light; since v = c/n, light travels slower (not faster) in water than in vacuum, nist/standard optics physics: refractive index of water n ≈ 1.33 (crc handbook of chemistry and physics); speed of light in a medium v = c/n, so light travels slower in water than in vacuum, nist/standard optics physics: speed of light in a medium equals c/n, where n is the refractive index; water has n ≈ 1.33 > 1, so light travels slower in water than in vacuum, not faster., nist/standard optics references on refractive index: speed of light in a medium equals c/n; water's refractive index n ≈ 1.33 (>1), so light travels slower in water than in vacuum, not faster., nist/standard optics references: speed of light in water c/n is approximately 2.25e8 m/s, slower than vacuum speed c = 2.998e8 m/s (refractive index of water ~1.33), nist/standard optics: speed of light in a medium equals c/n; water's refractive index n ≈ 1.33 > 1, so light travels slower in water (~2.25×10^8 m/s) than in vacuum (c = 2.998×10^8 m/s), nist/standard physics reference: refractive index of water is approximately 1.33, meaning light's phase velocity in water (~2.25e8 m/s) is slower than in a vacuum (c = 2.998e8 m/s); this follows directly from n = c/v., nist/standard physics reference: refractive index of water n ~= 1.33 (e.g. crc handbook of chemistry and physics), giving light speed in water v = c/n < c, nist/standard physics reference: refractive index of water n ≈ 1.33, meaning light travels at c/n ≈ 0.75c in water, slower than in vacuum (c)., nist/standard physics reference: refractive index of water n ≈ 1.33, so light speed in water = c/n ≈ 2.25×10^8 m/s, which is slower than the vacuum speed of light c = 2.998×10^8 m/s, nist/standard physics reference: refractive index of water n≈1.33 implies light speed in water is c/n < c, i.e. slower than in vacuum, nist/standard physics reference: speed of light in a medium v = c/n; water's refractive index n ≈ 1.33 > 1, so light travels slower in water than in vacuum, nist/standard physics references (e.g. refractive index tables): the speed of light in a medium equals c divided by that medium's refractive index (n≈1.33 for water), so light is slower in water than in vacuum, making the statement false, openstax.org, physics.info, physics.nist.gov, refractive index of water (n≈1.33) per standard physics references (e.g. nist/codata constants and optics textbooks); light speed in a medium v = c/n, so light is slower in water than in vacuum., refractive index of water is approximately 1.33 (n = c/v), meaning light travels at about c/1.33 ≈ 2.25×10^8 m/s in water, slower than its vacuum speed c ≈ 3×10^8 m/s. this is a standard physical constant found in physics references such as nist and standard optics textbooks., refractive index of water is approximately 1.33 (per standard physics references, e.g. nist/codata-based optics textbooks), meaning light travels at approximately c/1.33 in water, which is slower than its speed c in vacuum., science.nasa.gov, standard physics: refractive index of water (n≈1.33) is greater than 1, so light speed in water (v=c/n) is less than in vacuum, standard physics: refractive index of water n ~= 1.33, giving light speed in water v = c/n ~= 2.25e8 m/s, slower than c ~= 3.0e8 m/s in vacuum, www.aps.org, www.britannica.com, www.nist.gov, www.physicsclassroom.com
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