Final answer:
The speed of light, denoted as c, is a constant 299,792,458 m/s in a vacuum, though it's often approximated as 3x10^8 m/s. It is a crucial constant in physics that influences many laws and equations, and its value changes in different media due to the index of refraction. The distance light travels in a second and the distance between Earth and the Sun in light-seconds are important units of measurement in astronomy.
Step-by-step explanation:
The speed of light is a fundamental constant in physics, denoted as c. It is exactly 299,792,458 m/s in a vacuum, but for convenience, it is often rounded to 3x10^8 m/s. The speed of light is significant because it represents the maximum speed at which all energy, matter, and information in the universe can travel. It is also a critical component of various physical laws and equations, such as the equation connecting frequency (f) and wavelength (λ) of light: c = fλ. Additionally, light's speed changes when it passes through different media, which is described by the index of refraction due to the Law of Refraction. The light-second is a unit of length equivalent to the distance light travels in one second, which is also 3x10^8 m. One astronomical unit (AU) is the average distance between Earth and the Sun, about 1.50 x 10^11 m, which equates to approximately 500 light-seconds.