Computer Networks Quiz on Transmission Media For Class 12

✅ Answer: (c) Twisted pair cable

Twisted pair cable is a classic wired (guided) medium — pairs of insulated copper wires twisted together, commonly used for Ethernet/LAN connections and telephone lines. The other three are all wireless (unguided) media.

✅ Answer: (b) High data transfer rates

Fiber-optic cables use light pulses instead of electrical signals, allowing them to achieve very high data transfer rates and vast bandwidth — though they are more expensive than copper cabling.

✅ Answer: (c) Protecting signals from electromagnetic interference by twisting pairs of wires together

The wires are twisted together specifically to cancel out electromagnetic interference (crosstalk) picked up from nearby cables and electrical noise — the twisting is the core noise-reduction technique of this medium.

✅ Answer: (c) Television and cable internet services

Co-axial cable (with its central conductor, insulation, and shielding layers) is the standard medium for cable TV and cable internet connections.

✅ Answer: (c) Transmission of signals through light pulses instead of electricity

Since fiber-optic cables transmit data as pulses of light rather than electrical current, they are essentially immune to electromagnetic interference — a major advantage over copper-based cables.

✅ Answer: (c) Radio frequency (RF) communication

Radio frequency (RF) communication is the broad category that literally uses radio waves — covering everything from broadcast radio to certain wireless networking standards.

✅ Answer: (a) Limited range and the need for line-of-sight (an unobstructed path)

Infrared communication requires a clear line-of-sight path and works only over short distances — it can’t pass through walls or other obstacles, unlike radio waves.

✅ Answer: (b) Satellite communication and long-distance point-to-point links

Microwaves travel in straight lines and are widely used for satellite communication and long-distance terrestrial point-to-point links, typically requiring line-of-sight between towers or dishes.

✅ Answer: (d) Bluetooth communication

Bluetooth is specifically designed for short-range (typically up to about 10 meters), low-power wireless communication between nearby devices.

✅ Answer: (c) Generally low-cost infrastructure and equipment

Radio wave-based communication is generally associated with relatively low-cost infrastructure and equipment compared to fiber-optic or satellite-based systems. (Radio waves are actually susceptible to interference, not immune to it, and their data rates are typically lower than fiber-optic — so those options are incorrect.)

✅ Answer: (b) A connector commonly used for twisted pair (Ethernet) cables

RJ45 is the standard connector (the plug you see on Ethernet cables) used to attach twisted pair cables to network devices.

✅ Answer: (b) Boosts and retransmits signals to extend the network’s physical reach

A repeater receives a weakening signal and amplifies/retransmits it, allowing a network to extend beyond the distance a signal could otherwise travel without degrading.

✅ Answer: (b) Filters and forwards data selectively based on MAC addresses

A switch examines each incoming data frame’s destination MAC address and forwards it only to the specific device it’s meant for — much more efficient than a hub, which broadcasts every signal to all connected devices.

✅ Answer: (c) Determines the best path for data to travel between different networks

A router connects separate networks together (like your home network to the Internet) and decides the best path for each packet of data to reach its destination across those networks.

✅ Answer: (b) Gateway

A gateway acts as a translator between networks that use different protocols or architectures — for example, connecting a local network to a completely different type of external network. (A router, by contrast, typically connects networks that already share the same protocol suite.)

✅ Answer: (b) A hub broadcasts incoming data to ALL connected devices; a switch sends data selectively only to the intended device

A hub is a simple, “dumb” device — it broadcasts every incoming signal out to all connected ports. A switch is smarter — it reads each frame’s MAC address and forwards it only to the specific device it’s addressed to, reducing unnecessary network traffic.

✅ Answer: (b) To convert digital signals from a computer into analog signals for transmission (and back again) — MOdulator-DEModulator

Modem is short for Modulator-Demodulator — it converts a computer’s digital signals into analog form suitable for transmission over telephone/cable lines (modulation), and converts incoming analog signals back into digital data (demodulation).

✅ Answer: (b) A clear line-of-sight path between the transmitter and receiver, since microwaves travel in straight lines

Because microwaves travel in straight lines and don’t bend around obstacles well, communication towers or satellite dishes need a clear, unobstructed line-of-sight to each other for a reliable connection.

✅ Answer: (c) Fiber-optic cable

Fiber-optic cable offers by far the highest bandwidth among the three wired media, and since it transmits light rather than electrical signals, it’s essentially immune to electromagnetic interference — making it the preferred (though costlier) choice for high-speed, long-distance, interference-prone environments.

✅ Answer: (b) It allows a device to connect to a wireless network by sending and receiving radio signals

A WiFi card is the hardware component (built-in or external) that lets a device communicate wirelessly with a network router or access point, using radio frequency signals instead of a physical cable.