Kacapatan cahayo, atau bahaso Inggirih: lightspeed, di ruang hampa udaro , umumnyo dilambangkan c,[1] adolah universal konstan fisika pantiang pado banyak bidang fisika. Nilai eksaknyo didefinisikan sabagai 299,792,458 meter per detik (kiro-kiro 583 juta knots; 300,000 kilometer per detik; 186,000 mil per detik; 671 juta mil per jam). Hal iko topek basobok, alah sapakek jo internasional, meteran didefinisikan sabagai panjang jalan nan batuju dek cahayo pado ruang hampa salamo solang wakatu dari 1/299 792 458 datiak.
| Kacapatan cahayo |
|---|
 Kilek dapek sabagai contoh alami mangukua laju cahayo, dapek pulo dangan listrik togangan tenggi diateh 12000 Volt nan biaso dipakai pado industri. |
| Simbol umum | c atau c |
|---|
| Satuan lainnyo | Tm/s , mps, m/s |
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| Dalam satuan pokok SI | m/s |
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- ↑ "The origins of the letter c being used for the speed of light can be traced back to a paper of 1856 by Weber and Kohlrausch [...] Weber apparently meant c to stand for 'constant' in his force law, but there is evidence that physicists such as Lorentz and Einstein were accustomed to a common convention that c could be used as a variable for velocity. This usage can be traced back to the classic Latin texts in which c stood for 'celeritas', meaning 'speed'."
