AQA · GCSE · Computer Science
Course version: 8525 · Version from Sept 2020
Students should know that wired networks can use different types of cable…
Full specification wording
Fundamentals of computer networks: Students should know that wired networks can use different types of cable such as fibre and copper and when each would be appropriate.
Wired networks carry signals along a physical medium, and the medium chosen affects speed, distance, cost and interference.
Checked against the AQA 8525 specification (opens in a new tab) on .
- Point 13 of 50
Study notes
From the checked teaching notes for this specification point.
The idea
Wired networks carry signals along a physical medium, and the medium chosen affects speed, distance, cost and interference. Copper cable, such as twisted pair or coaxial, carries electrical signals; it is cheap, easy to install and fine for short runs within a building, but signal strength drops over long distances and it picks up electromagnetic interference. Fibre optic cable carries pulses of light along glass strands; it supports very high bandwidth over long distances with little loss and is immune to electrical interference, but it costs more and is harder to install and repair. So fibre suits long-distance or high-demand backbones and links between buildings, while copper suits short, low-cost connections to individual devices. A question may give a scenario and ask which cable is appropriate, so match the cable's properties to the need.
What earns the marks
- Copper cable carries electrical signals and is relatively cheap and easy to install, making it suitable for short connections within a building.
- Copper suffers signal loss over long distances and is affected by electromagnetic interference.
- Fibre optic cable carries light signals and supports high bandwidth over long distances with little signal loss.
- Fibre is immune to electrical interference but is more expensive and harder to install or repair.
- Choosing a cable means matching its properties to the scenario, for example fibre for a long backbone link and copper for short device connections.
Common mistakes and how to put them right
Assuming fibre is always the correct answer regardless of cost or distance.
Put it right: Match the cable to the scenario's needs, since copper is cheaper for short runs.
Thinking copper carries light or fibre carries electricity.
Put it right: Copper carries electrical signals and fibre carries light.
Believing fibre is affected by electrical interference.
Put it right: Fibre is immune to it because it uses light, not electricity.
Exam tips
- Read the scenario for clues about distance, bandwidth and budget before choosing a cable.
- Link each cable to a property: copper is cheap but loses signal over distance; fibre is fast over distance but costs more.
- Eliminate options that swap the signal type, such as claiming fibre uses electrical signals.
Try the lesson
The start of the Fundamentals of computer networks: Students should know that wired networks can use different types of cable such as fibre and copper and when each would be appropriate. lesson, made from checked teaching notes for this specification point.
Have a go first
A company needs to connect two buildings that are 2 km apart and must carry very large amounts of data quickly between them. Which type of cable is most appropriate for this link?
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