What is the speed of light in a vacuum?

• A. 300,000 km/s
• B. 299,792,458 m/s
• C. 150,000 km/s
• D. 3.00 × 10^6 m/s

Answer: (B)

The speed of light in a vacuum is defined as 299,792,458 meters per second. This value is a fundamental constant in physics and is crucial for various scientific calculations, including those in electrical and computer engineering. The definition stems from extensive empirical measurements and has been adopted as an exact value within the International System of Units (SI).

This precise measurement is significant because it underpins theories in physics, such as Einstein's theory of relativity, and establishes a foundation for our understanding of the electromagnetic spectrum, which includes radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays, and gamma rays.

In contrast, while 300,000 km/s is a commonly used approximation of the speed of light, it is less accurate than the exact scientific figure. The other options provide values that are either significantly lower or incorrectly expressed and do not reflect the established speed of light in a vacuum. Understanding this value helps in fields like telecommunications, where light signals are fundamental to data transmission over fiber optic cables.