Question
Why is the electrical length of a coaxial cable longer than its physical length?
Answer Options
- A) Skin effect is less pronounced in the coaxial cable
- B) Skin effect is more pronounced in the coaxial cable
- C) Electromagnetic waves move faster in coaxial cable than in air
- D) Electromagnetic waves move more slowly in a coaxial cable than in air
Correct Answer: D
Explanation
The electrical length of a cable is its length expressed in terms of the wavelength (\lambda) of the signal inside the cable. If the electrical length is longer than the physical length, it means the wavelength of the signal inside the cable is shorter than the wavelength in free space, implying the wave is traveling slower.
This reduction in speed is caused by the insulating material (dielectric). Therefore, the electrical length of a coaxial cable is longer than its physical length because electromagnetic waves move more slowly in a coaxial cable than in air. This reduced speed is quantified by the velocity factor (\text{VF}), which is always less than 1.
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