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Unit-4, 5: Physical Layer, Transmission Medium Prepared by: Mousumi Saha

Date: 13-04-11 Lecturer, Department of IT

Q1: what is meant by switching?

Answer: Switch is a connecting device and switching is the procedure to connect multiple

communication devices.

Q2: what is meant by multiplexing?

Answer: Multiplexing is sending multiple signals or streams of information on a carrier at the same

time in the form of a single, complex signal and then recovering the separate signals at the receiving

end.

Q3: what is meant by topology?

Answer: Topology nothing but a connection procedure, Network topology is the layout pattern of

interconnections of the various elements.

Q4: what is the difference between ring and star topology?

Answer: In case of star there is central device by which all the nodes or computer are connected and

in a ring topology each node is connected to two other nodes creating a ring.

Q5: What is the difference between multiplexing and demultiplexing?

Answer: Multiplexing (also known as muxing) is a method by which multiple analog message signals

or digital data streams are combined into one signal over a shared medium. And demultiplexing is

the opposite of multiplexing.

For example, in telecommunications, several telephone calls may be carried using one wire.

Multiplexing originated in telegraphy, and is now widely applied in communications.

Q6: what is transmission medium?

Answer: Transmission medium means by which signal are transferring from one end to another end.

Q7: How can we say that it is guided or unguided media?

Answer: When you are talking in telephone, your voice is transfer in to a signal and it goes by a cable

to other end. Unguided transmission media is data signals that flow through the air. They are not

guided or bound to a channel to follow. They are classified by the type of wave propagation.

Q8: what is cu wire?

Answer: Cu wire is copper wire.

Q9: why insulating material is used in coaxial cable?

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Answer:

Q10: what is terrestrial?

Answer: Terrestrial refers to things related to land or the planet Earth. Terrestrial television is a

mode of television broadcasting which does not involve satellite transmission or cables

typicallyusing radio waves through transmitting and receiving antennas or aerials.

Q11: How can we say that it is thick and thin coaxial cable?

Answer: Coaxial cable with a diameter of .393 inches is called thick coaxial cable. Thinnet cable is a

flexible coaxial cable about 0.64 centimetres (0.25 inches) thick. Because Thicknet cable's copper

core is thicker than a Thinnet cable core. The thicker the copper core, the farther the cable can carry

signals.

Q12: why insulating material is used in coaxial cable?

Answer: A cable consisting of an electrically conductive wire surrounded by a layer of insulating

material, a layer of shielding material, and an outer layer of insulating material, usually plastic or

rubber. The purpose of the shielding layer is to reduce external electrical interference. Coaxial cables

are used for transmission of high-frequency audio, video, computer network and other signals.