ðə tɹænsmˈɪʃən kˌoʊɪfˈɪʃənt ɪz ɐ mˈɛʒɚɹ ʌv hˌaʊ mˈʌtʃ əvən ɪlˌɛktɹoʊmɐɡnˈɛɾɪk wˈeɪv lˈaɪt pˈæsᵻz θɹuː ɐ sˈɜːfɪs ɔːɹ ɐn ˈɑːptɪkəl ˈɛlɪmənt.
The transmission coefficient is a measure of how much of an electromagnetic wave (light) passes through a surface or an optical element.