Light travels fastest through which of the following?A airB glassC vacuumD water

Break Down the Problem

1. Identify the mediums listed: air, glass, vacuum, and water.
2. Determine the speed of light in each medium.

Relevant Concepts

1. The speed of light in a vacuum is approximately $c = 3 \times 10^8$ m/s.
2. The speed of light in different mediums can be described by the formula: $v = \frac{c}{n}$ where $n$ is the refractive index of the medium.

Analysis and Detail

1. Vacuum: The refractive index $n = 1$, so the speed of light $v = c$.
2. Air: The refractive index $n \approx 1.0003$, giving $v \approx \frac{c}{1.0003}$.
3. Glass: The refractive index $n \approx 1.5$, so $v \approx \frac{c}{1.5}$.
4. Water: The refractive index $n \approx 1.33$, leading to $v \approx \frac{c}{1.33}$.

Verify and Summarize

• The fastest speed of light is in a vacuum.
• Among the other options, air has a speed close to that in a vacuum, while light travels slower in glass and water.

Final Answer

C. vacuum