Data Transmission Media
12 Grade 10 Computer Studies questions on Data Transmission Media, with worked marking schemes. 12 questions are available on this topic in full.
Question 1
1 markA farmer in Laikipia needs a network link between the homestead and a borehole pump house 2 kilometres away across open grazing land where digging a trench is not allowed. Which medium is most suitable?
A. A point-to-point microwave radio link
B. Category 5e UTP cable
C. Coaxial cable laid on the surface
D. A Bluetooth connection
(1 mark)
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3 marksDescribe what is meant by bandwidth of a transmission medium and state one factor that reduces the effective bandwidth of a cable.
(3 marks)
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1 markA technician is running a network cable inside the roof space of a school workshop in Thika, directly alongside the mains cable feeding the welding machines. Which transmission medium is LEAST affected by the electromagnetic interference produced by that machinery?
A. Fibre optic cable
B. Unshielded twisted pair cable
C. Shielded twisted pair cable
D. Coaxial cable
(1 mark)
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4 marksDistinguish between guided and unguided transmission media, giving one example of each.
(4 marks)
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1 markIn a twisted pair cable, the pairs of wires are twisted around each other mainly in order to:
A. allow the cable to carry electricity as well as data
B. make the cable stronger so it does not snap when pulled
C. increase the number of wires that fit in the sheath
D. reduce crosstalk and interference between the pairs
(1 mark)
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3 marksState three advantages of using fibre optic cable instead of copper cable for the backbone link between the administration block and the library of a large school.
(3 marks)
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1 markA tea factory in Kericho links its weighing shed to the office block, a distance of about 300 metres, using a single run of Category 6 UTP cable. The link keeps dropping. What is the most likely cause?
A. UTP cannot carry data in a rural area
B. Category 6 cable only works indoors
C. The cable run exceeds the 100 metre maximum segment length for UTP
D. Copper cable cannot be used between two buildings at all
(1 mark)
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1 markHow does data travel along a fibre optic cable?
A. As radio waves bounced between two metal shields
B. As magnetic pulses induced in a braided copper mesh
C. As electrical pulses flowing through a copper core
D. As pulses of light reflected along a glass or plastic core
(1 mark)
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4 marksA maize milling plant in Nakuru has its network cables damaged repeatedly by rats and by dust. Suggest two practical measures the technician can take to protect the cabling, and explain how each helps.
(4 marks)
Marking scheme
Two measures, each with a supporting explanation (2 + 2): 1. Run the cables inside conduit/trunking or armoured ducting — rats cannot reach the insulation and dust does not settle on connectors. 2. Mount cable trays high on the wall or in the ceiling away from the floor — reduces rodent access and physical damage from moving equipment. 3. Use sealed/dust-proof patch cabinets for terminations — keeps milling dust out of the contacts. 4. Replace vulnerable copper runs with armoured fibre — no copper for rodents to gnaw for the metal and no corrosion from dust and moisture. (Accept any two developed measures.)
Question 10
4 marksExplain two reasons why a school in a hilly part of Murang'a might choose a wireless link rather than a cable to connect a classroom block standing on the opposite side of a valley.
(4 marks)
Marking scheme
Two reasons, each with a point for the reason and a point for the explanation (2 + 2): 1. Cost/labour of cabling — trenching or suspending cable across a valley is expensive and may need poles or permission over land that is not the school's. 2. Terrain obstacle — the ground between is broken or steep, so a cable run would be difficult to lay and easy to damage; a radio link only needs line of sight between two masts. 3. Speed of installation — a wireless link can be set up in a day, while cabling takes far longer. (Accept any two developed reasons.)
Question 11
1 markWhich statement about infrared as a transmission medium is correct?
A. It requires a clear line of sight between the sending and receiving devices
B. It can transmit reliably over several kilometres outdoors
C. It uses a copper conductor to guide the signal
D. It passes easily through walls, so rooms need not be in line of sight
(1 mark)
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4 marksOutline two limitations of using microwave transmission for a link between a coffee factory in Nyeri and its head office in Nairobi.
(4 marks)
Marking scheme
Two limitations, each stated and briefly outlined (2 + 2): 1. Requires clear line of sight — hills, tall buildings or trees between the two points block the signal, so repeater stations may be needed. 2. Affected by weather — heavy rain, mist or storms attenuate the signal and reduce reliability during the wet season. 3. Signal can be intercepted since it travels through open air, raising security concerns. 4. High initial cost of masts, dishes and licensing of the frequency. (Accept any two.)
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