Cahaya mempunyai kelajuan 300 000 000 km/s ada ruang vakum dan kelajuan akan berkurangan mengikut ketelusan sesuatu ruang atau medium (Coaton & Marsden, 1997).
Light has a speed of 300 0000 0000 km/s there is a vacuum of space and speed will be reduced in accordance with the transparency of a space or medium (Coaton & Marsden, 1997).
Light has a speed of 300 million km / s there is a vacuum and the speed will be reduced in accordance with the transparency of a space or medium (Coaton & Marsden, 1997).