---
title: "Coaxial cable vs optical fiber"
subject: "Data Communication"
chapter: 4
key: "semester_5/data_communication:coax-vs-fiber"
source: https://www.bctengineer.com/q/semester_5/data_communication/coax-vs-fiber
site: BCT Engineering
---

# Coaxial cable vs optical fiber

Data Communication · Chapter 4: Transmission Media

- Asked in: 2070 Chaitra, 3 marks
- Video: [Fiberoptic vs Coaxial: The Difference](https://www.youtube.com/watch?v=PeC_RLGxD70) — Adeptis Academy
- Answer checked by Claude Sonnet 5.5 on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_5/data_communication/coax-vs-fiber
- Whole chapter: https://www.bctengineer.com/md/semester_5/data_communication/chapter-4

## Question

Differentiate between coaxial cable and optical fiber.

## Short answer

Coaxial cable uses electrical signals over copper, has higher attenuation, limited bandwidth (up to 500 MHz), and is susceptible to EMI. Optical fiber uses light over glass/plastic, offers terahertz bandwidth, very low attenuation, immunity to EMI, and longer repeater spacing.

## Answer

| Point | Coaxial cable | Optical fibre |
|---|---|---|
| Signal | Electrical | Light |
| Core material | Copper conductor | Glass / plastic |
| Bandwidth | Up to 500 MHz (hundreds of Mbps) | Terahertz range (Gbps-Tbps) |
| Attenuation | High (7 dB/km at 10 MHz) | Very low (0.2-0.5 dB/km) |
| Repeater spacing | 1-9 km | 40 km or more |
| EMI / crosstalk | Affected (reduced by shield) | Immune |
| Security | Can be tapped easily | Hard to tap |
| Cost | Cheaper | Costlier |
| Installation | Easier | Needs skilled work; fragile |
| Weight | Heavy, thick | Light, thin |
| Use | Cable TV, old Ethernet | Backbones, FTTH |

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Which has very low attenuation (0.2-0.5 dB/km)?
   A. Coaxial cable
   B. Both
   C. Neither
   D. Optical fibre
   Answer: D. Coax is about 7 dB/km at 10 MHz. (Key point: Attenuation)

2. Which is easily tapped?
   A. Optical fibre
   B. Coaxial cable
   C. Neither
   D. Both equally hard
   Answer: B. Fibre is hard to tap. (Key point: Security)

3. Repeater spacing for coax versus fibre:
   A. Coax 40 km; fibre 1-9 km
   B. Both 40 km
   C. Coax 1-9 km; fibre 40 km or more
   D. Coax 100 m; fibre 1 km
   Answer: C. Fibre needs far fewer repeaters. (Key point: Repeater spacing)

## Related in Data Communication

- [Optical fiber vs satellite transmission](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Aoptical-fiber-vs-satellite) — Data Communication, chapter 4
- [Optical fiber advantages over coax and twisted pair](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Afiber-advantages) — Data Communication, chapter 4, asked 3×
- [Short note: Multi mode optical fiber](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Amultimode-fiber-short-note) — Data Communication, chapter 4
- [Short note: Optical fiber versus STP](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Aoptical-fiber-vs-stp) — Data Communication, chapter 4

## Related in other subjects

- [Optical fiber and its advantages](https://www.bctengineer.com/question.md?key=semester_2%2Fbasic_electronics_engineering%3Aoptical-fiber-advantages) — Basic Electronics Engineering, chapter 5, asked 5×
- [Compare twisted pair, coaxial, fiber](https://www.bctengineer.com/question.md?key=semester_7%2Fcomputer_networks_and_security%3Acompare-twisted-coax-fiber) — Computer Networks and Security, chapter 2
- [Optical fiber, NA, single vs multimode](https://www.bctengineer.com/question.md?key=semester_1%2Fengineering_physics%3Aoptical-fiber-na-acceptance-mode-comparison) — Engineering Physics, chapter 6
- [Fiber optic vs copper cable](https://www.bctengineer.com/question.md?key=semester_8%2Ftelecommunications%3Afiber-vs-copper-applications) — Telecommunications, chapter 2