Transmission Medium — Long Answer Questions (Class 9 Computer Applications)
Medium Level (Application & Explanation)
Q1. Explain the difference between guided media and unguided media with examples and one key advantage of each.
Answer:
Guided media, also called wired media, uses physical paths like Ethernet cables, coaxial cables, and optical fiber to carry signals. Guided media provide a stable and secure connection and are less affected by external interference. For example, an Ethernet cable connects a laptop to a router in a home network. Unguided media, or wireless media, transmits signals through the air using radio waves, microwaves, or infrared, with examples such as Wi‑Fi and satellite communication. A key advantage of guided media is reliable high-speed transfer, while a key advantage of unguided media is mobility and easy installation for devices like smartphones and tablets.
Q2. Describe the structure and common uses of a coaxial cable, and explain why it was widely used for television services.
Answer:
A coaxial cable has a central copper conductor surrounded by insulation, then a metallic braided shield, and an outer jacket. This layered structure gives it good protection against electromagnetic interference and allows it to carry high-frequency signals. Coaxial cables were widely used for television services because they can transmit clear audio and video signals over long distances without much loss. They were also used in early LANs. The two main types are baseband (single signal over short distances) and broadband (multiple signals over longer distances), making coaxial flexible for cable TV companies and for delivering multiple channels to many homes.
Q3. Explain the difference between a crossover Ethernet cable and a straight-through Ethernet cable, and give a real-life scenario where each is used.
Answer:
A straight-through Ethernet cable connects devices of different types, for example a computer to a router or switch; the wiring on both ends follows the same pin order. A crossover cable is wired so that transmit and receive pairs are swapped, allowing two similar devices, like two computers, to communicate directly without a hub or switch. A real-life scenario for straight-through is connecting a home PC to the Wi‑Fi router for internet access. A real-life scenario for crossover is setting up a direct LAN game between two laptops without a router. Knowing which cable to use helps set up networks quickly and correctly.
Q4. Describe how an optical fiber cable works, list its main advantages, and mention one practical setting where it is the best choice.
Answer:
An optical fiber cable transmits data as pulses of light through a thin glass core surrounded by cladding and protective layers. The light signals travel with very low loss and are immune to electromagnetic interference. Main advantages include extremely high bandwidth, very fast data transfer, and long-distance transmission without repeaters. A practical setting where fiber optics are the best choice is in internet backbone connections or data centers, where large amounts of data must move quickly and reliably. Internet Service Providers use fiber to deliver high-speed broadband to urban areas because it supports streaming, cloud services, and many users simultaneously.
Q5. Explain Wi‑Fi — how it works, its advantages and disadvantages, and one example where its mobility is most useful.
Answer:
Wi‑Fi uses radio waves to create a Wireless Local Area Network (WLAN) that lets devices like smartphones, laptops, and tablets connect to the internet without cables. A Wi‑Fi router transmits and receives data to and from devices using radio signals on standard frequencies. Advantages include easy setup, mobility, and the ability to connect many devices without wiring. Disadvantages are lower speed than wired connections, higher power consumption, and susceptibility to interference and signal loss. Wi‑Fi mobility is most useful in places like cafés or libraries, where people move around and use laptops or phones while staying connected.
High Complexity (Analytical & Scenario-Based)
Q6. A small school plans to set up a computer lab for 30 students. Compare the use of Ethernet (guided) versus Wi‑Fi (unguided) for this lab, and recommend the best option with reasons.
Answer:
For a 30‑student computer lab, Ethernet offers stable, high-speed, low-latency connections and reduces interference—important for tasks like online exams or multimedia lessons. It requires cabling and switches, raising installation cost and limiting device mobility. Wi‑Fi allows easy device placement and student mobility, with lower upfront cabling cost, but may suffer from congestion, interference, and slower speeds when many devices connect. Recommendation: use Ethernet for desktop computers that need reliability (like exam stations) and provide Wi‑Fi as a supplementary network for portable devices. This hybrid approach balances performance, cost, and flexibility.
Q7. An Internet Service Provider (ISP) must choose between upgrading a city’s network with coaxial broadband or optical fiber. Analyze the long-term benefits and challenges of choosing fiber optics over coaxial cable.
Answer:
Choosing fiber optics gives the ISP long‑term benefits: vastly higher bandwidth, faster speeds, and future‑proof capacity for increasing demand (streaming, cloud, IoT). Fiber is immune to electromagnetic interference and supports long-distance transmission with fewer repeaters. Challenges include higher initial deployment cost, specialized installation skills, and fragility that needs careful handling. Coaxial is cheaper to upgrade and uses existing infrastructure, but its bandwidth ceiling is lower and it may need frequent upgrades. Long-term, fiber yields better performance and lower maintenance per unit data, making it the best investment for cities expecting growth in digital services.
Q8. A news reporter is in a remote region with no wired internet. Compare satellite communication and mobile cellular networks for sending a live report, and suggest the more reliable option with reasons.
Answer:
In remote regions without wired internet, mobile cellular networks (if available) provide convenient internet via towers and can support live reporting with lower latency, but coverage is often spotty and bandwidth may be limited. Satellite communication offers wider coverage and works almost anywhere on Earth, as long as there is a clear sky view. Satellites can carry large amounts of data and are dependable for long-distance transmission. For a remote area with unreliable or no cell coverage, satellite communication is more reliable for sending a live report. The trade-off is higher cost and potential latency, but it ensures connectivity when cellular networks are absent.
Q9. A gaming café owner wants the lowest possible latency and most stable connection for competitive online gaming. Should they choose fiber optic backbone with Ethernet connections to each PC, or a Wi‑Fi only setup? Explain with technical reasons.
Answer:
For competitive online gaming, the owner should choose a fiber optic backbone combined with wired Ethernet connections to each PC. Fiber provides high upstream and downstream bandwidth from the ISP to the café, while Ethernet offers low latency, consistent throughput, and minimal packet loss at each workstation. A Wi‑Fi only setup is more convenient, but wireless signals suffer from interference, variable latency, and jitter, which degrade gaming performance. Wired Ethernet reduces lag and disconnections, giving gamers a stable environment. Thus, fiber plus Ethernet delivers the best technical performance for competitive play despite higher setup cost.
Q10. Design a hybrid network for a medium-sized company that has an office, a warehouse, and several field teams. Explain which transmission media you would use for each part and why.
Answer:
For the office, use optical fiber for the main backbone to provide high-speed internet and internal data transfer, combined with Ethernet wiring (guided) to desktop PCs and critical servers for stability. For the warehouse, use Wi‑Fi to allow mobile scanners, tablets, and inventory devices to move freely, with Ethernet for fixed systems like inventory servers and security cameras; where long distances exist between buildings, use fiber or coaxial as needed. For field teams, rely on cellular networks and satellite backup—cellular for routine mobile access and satellite for remote areas without coverage. This hybrid mix balances speed, mobility, reliability, and cost to meet varied business needs.