COMPUTER STUDIES QUESTIONS WITH ANSWERS
With the aid of a diagram, describe the physical structure of a coaxial cable.Coaxial cables are made up of a central copper core that is insulated with a dialectric material (insulator), an aluminium foil, a braided shield (or mesh conductor) and an outer plastic covering. This insulation makes the cable resistant to electromagnetic interference.
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Describe the electrical properties of coaxial cables that made it suitable as a network backbone before the advent of fibre optic cables.Coaxial cables support high bandwidth compared to UTP cables; hence, a preferred choice for laying network backbones. In addition, it conducts data using direct current and is more immune to electromagnetic interference thus it is preferred for EMI prone places.
Using illustrations, differentiate between thinnet and thicknet coaxial cables.A thinnet or thin coaxial cable has one dielectric insulator (Fig. 1.5 (a)) while a thicknet or thick coaxial cable has two dielectric insulators (Fig. 1.5 (b)).
List five sources of electromagnetic interference that may cause data loss in communication systems.19/11/2022 List five sources of electromagnetic interference that may cause data loss in communication systems.
ADVANTAGES OF SETTING UP A COMPUTER NETWORK USING TWISTED PAIR CABLES
Disadvantages OF SETTING UP A COMPUTER NETWORK USING TWISTED PAIR CABLES
State the components needed for each of the following task in a fibre network.
Using illustrations, differentiate between unshielded and shielded twisted pair cables.The two types of twisted pair cables are made up of two insulated copper wires wound around each other to form a helix.
However, the unshielded twisted pair (UTP) cables do not have an external shield to guard against electromagnetic interference (EMI) from the environment as shown in Fig 1.3 (a). Shielded twisted pair (STP) cables, on the other hand, have an external shield which guards against environmental EMI (Fig. 1.3 (b)) Why is the use of the two wire open lines cables not common nowadays.The cables suffer from electromagnetic interference (EMI) because they are not shielded from environmental 'noise'. They pick electromagnetic signals from the environment; hence, they introduce noise in the communication channel. The magnetic fields around individual cables also interfere with each other during transmission leading to high radiation losses through a process called crosstalk.
Describe how the two wire open lines cable works in data transmission.The cable is made up of two copper wires running parallel to each other and separated by a plastic insulator. The copper wires are good signal conductors and are cheap to buy.
Communication media can be classified into two broad categories. State the two categories giving examples of each.
List four types of guided transmission media.
List four examples of wide area networks (WANs).
Apart from size, what other properties are unique to LANS as opposed to MANS or WANs?
The following are acronyms for some types of networks. Write them in full.
Computer networks can be classified according to their geographical size and ownership. Explain each of the following with regard to this classification. (a) LAN (b) MAN (c) WAN
State five limitations of networking.
State five reasons why computer networks are important.
Identify two application areas each where simplex, half- duplex and full-duplex communication modes are used. Simplex communication is used in public broadcasting where receivers do not have to reply, for example, in radio and television broadcasting; some missile launching systems which only receive commands from the launcher, and are not set to communicate back. Half-duplex communication is used in two way (one way at a time) high frequency radios such as the walkie-talkie radios;half-duplex ethernet where only one computer is allowed to use the transmission media at a time. Full-duplex communication is used in computer networks such as in full-duplex ethernet networks where one pair of UTP cable is used for sending data and another one for receiving; voice telephone networks (mobile phones) where one frequency is set for sending and another one for receiving data (also called frequency-division duplex).
When you look at water bodies like lakes or seas, the water appears blue from a distance yet at a closer look it is colourless. Explain this phenomena. The seven colours in white light have different attenuation distances in water, with blue having the longest attenuation distance. Therefore, when the light strikes vast water bodies, the other colours attenuate faster (are filtered) leaving the predominant blue colour. Hence, the deeper the water body, the more blue it appears.
Explain the following data communication modes:Â (a) simplex (b) half-duplex (c) full-duplex14/11/2022 Explain the following data communication modes: (a) simplex (b) half-duplex (c) full-duplex (a) Simplex communication is the mode in which data signals flow in one direction only in a communication channel and cannot flow back in the opposite direction. (b) Half-duplex communication is the mode in which data signals flow in both directions of the communication channel, but they do so in one direction at a time. (c) Full-duplex communication is the mode in which data signals flow in both directions in a communication channel simultaneously.
Explain the importance of repeaters in a communication system. Different mediums have different attenuation rates. To avoid signal loss in the medium due to attenuation, repeaters are introduced at appropriate points on the network (attenuation points) to receive the weak signal, clean it, amplify it then send it over to the next section of the medium in the network.
When data is being transmitted from a source to a destination, it could face challenges that may cause it to get lost. Highlight these challenges.
(a) State the name used for this technique.Multiplexing Using an illustration, depict how this concept worksA multiplexer carries many data signals on the same physical transmission channel from a source while a demultiplexer separates the combined signals at the destination
Differentiate between the following:(a) Signal modulation and demodulationModulation is the process of superimposing a low frequency (low power) data signal on a high frequency (high power) carrier signal to enable its transmission over long distances in the medium. Demodulation, on the other hand, is the extraction of a data signal from a modulated carrier signal which has been used to transmit over the network. (b) Modulation rate and baud rate Modulation rate is the term used to express the performance of a modulating circuit. It shows the rate at which the modulated signal is processed to represent data. It is measured in pulses per second or the baud hence, it also known as baud rate. (c) Bandwidth and throughputBandwidth is the maximum rate at which a transmission channel can convey data. It is measured in bits per second (bps). On the other hand, throughput is the instantaneous rate at which a particular channel is transmitting data, and may be swab equal to or lower than the maximum bandwidth available. (d) Baseband and broadband signalsA baseband signal takes the entire bandwidth of the physical channel; hence, it is transmitted alone. A broadband signal, on the contrary, divides the physical channel into many frequency channels; hence, it allows many signals to be transmitted through the medium in a multiplexed manner.
A signal wave has three salient properties: frequency, wavelength and amplitude. Describe each one of them.
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