---
title: "Define transmission media"
subject: "Computer Networks and Security"
chapter: 2
key: "semester_7/computer_networks_and_security:define-transmission-media"
source: https://www.bctengineer.com/q/semester_7/computer_networks_and_security/define-transmission-media
site: BCT Engineering
---

# Define transmission media

Computer Networks and Security · Chapter 2: Physical Layer

- Asked in: 2071 Shrawan, 2 marks; 2074 Chaitra, 3 marks (asked 2 times)
- Video: [Transmission media | Computer Networking | CN | Lec-37](https://www.youtube.com/watch?v=VyaLZaaUPVM) — Education 4u
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_7/computer_networks_and_security/define-transmission-media
- Whole chapter: https://www.bctengineer.com/md/semester_7/computer_networks_and_security/chapter-2

## Question

What is transmission media?

## Short answer

Transmission media are physical or wireless channels carrying data signals from sender to receiver. They are guided (twisted pair, coaxial, fiber) or unguided (radio, microwave, infrared), chosen based on bandwidth, attenuation, cost, distance, installation, and noise immunity.

## Answer

**Transmission media** are the physical or wireless channels through which data signals travel from a sender to a receiver. They form the layer below the physical layer in the OSI model.

They are of two types:
- **Guided (bounded) media:** the signal follows a physical path, such as twisted pair, coaxial cable and optical fibre.
- **Unguided (unbounded) media:** the signal travels through air or space without a conductor, such as radio waves, microwaves and infrared.

The choice of medium depends on bandwidth, attenuation, cost, distance, installation, and noise immunity.

## Check yourself

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

1. What is transmission media?
   A. Software that encrypts data
   B. Physical or wireless channels through which data signals travel from sender to receiver
   C. A type of protocol
   D. A switch
   Answer: B. It is the channel that carries signals between sender and receiver. (Key point: Definition)

2. Which are guided (bounded) media?
   A. Twisted pair, coaxial cable, optical fibre
   B. Radio waves, microwaves, infrared
   C. Wi-Fi and satellite
   D. Bluetooth only
   Answer: A. Guided media give the signal a physical path. (Key point: Guided examples)

3. Which factors decide choice of medium?
   A. Bandwidth, attenuation, cost, distance, installation, noise immunity
   B. Only colour
   C. Only brand
   D. Only the OS
   Answer: A. Medium selection depends on bandwidth, attenuation, cost, distance, installation and noise immunity. (Key point: Choice factors)

## Related in Computer Networks and Security

- [Guided and other transmission media](https://www.bctengineer.com/question.md?key=semester_7%2Fcomputer_networks_and_security%3Atransmission-media-explain) — Computer Networks and Security, chapter 2, asked 3×

## Related in other subjects

- [Guided and unguided transmission media](https://www.bctengineer.com/question.md?key=semester_8%2Ftelecommunications%3Atransmission-media-explain) — Telecommunications, chapter 2, asked 2×
- [Guided vs unguided transmission media](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Aguided-vs-unguided-media) — Data Communication, chapter 4
- [Transmission characteristics of guided media](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Aguided-media-transmission-characteristics) — Data Communication, chapter 4
- [Wired vs wireless media; four-wire and hybrid](https://www.bctengineer.com/question.md?key=semester_8%2Ftelecommunications%3Awired-wireless-four-wire-hybrid) — Telecommunications, chapter 2, asked 2×