Which speed value is given for electromagnetic energy in coax cables?

Which speed value is given for electromagnetic energy in coax cables?

• A. 285,000,000 meters per second.
• B. 299,792,458 meters per second.
• C. 250,000,000 meters per second.
• D. 100,000,000 meters per second.

Answer: (A)

Propagation speed of electromagnetic energy along a coax is the velocity at which the wave travels, set by the dielectric around the conductors. It is a fraction of the speed of light in vacuum, determined by the dielectric’s properties (v ≈ c/√ε_r). In teaching and quick calculations, a rounded figure near the speed of light is often used, about 2.85×10^8 m/s, which is roughly 0.95c. That makes it a convenient and representative value for coax energy propagation, which is why this option is the best match. The exact vacuum speed (about 3.00×10^8 m/s) is not typically quoted for coax since the signal slows in the dielectric, and the other values are simply farther from the common rounded approximation used in practice.

Propagation speed of electromagnetic energy along a coax is the velocity at which the wave travels, set by the dielectric around the conductors. It is a fraction of the speed of light in vacuum, determined by the dielectric’s properties (v ≈ c/√ε_r). In teaching and quick calculations, a rounded figure near the speed of light is often used, about 2.85×10^8 m/s, which is roughly 0.95c. That makes it a convenient and representative value for coax energy propagation, which is why this option is the best match. The exact vacuum speed (about 3.00×10^8 m/s) is not typically quoted for coax since the signal slows in the dielectric, and the other values are simply farther from the common rounded approximation used in practice.