Tiān-liû (電流; electric current) sī chi̍t tīn tiān-hô ê liû-tōng. Tiān-liû ê bu̍t-lí ì-gī sī tan-ūi sî-kan lāi thong-kòe bó͘ chi̍t-ê chia̍t-bīn ê tiān-hô sò͘-liōng; i-ê kok-chè tan-ūi sī ampere (A), ta̍k bió-cheng keng-kòe 1 coulomb ê tiān-liōng (C/s).