Computer full notes of class 11 chapter 3
Fill in the blanks with the correct words:
1 = Converts , 2 = Unbounded , 3 = 22000 , 4 = Guided-media , 5 = Full
duplex , 6 = Sysnchronous , 7 = 100 meters , 8 = Modulator-Demodulator , 9 = Line of sight , 10 = Fiber optic
Computer full notes of class 11 chapter 3 MCQS end.
Short And Long Questions
Question 1 Answer.
Data communication: The transmission of data from one place to another place is called data communication.
The transmission of data from one computer or device to another computer or device is called data communication.
Question 2 Answer.
Data communication system: The entire system which is responsible for transmission of data from one point to another point is called data communication system.
The system which performs data communication is called data communication
There are five basic components or elements of a data communication system which are:
Sender or source
Receiver or sink
Sender: It is the computer or other device which transmits data.
Channel encoder: It is a device which converts digital data into a form that can pass along communication medium.
Communication medium: It is the path way over which data is carried or transmitted from sender to receiver.
Channel decoder: It is a device which converts the data from some other form back into digital form.
Receiver: It is the computer or other devices which receives the data.
Transmission media: Transmission medium (plural media) is an important component of data communication system or a computer network. It interconnects computers or other devices in data communication system or a computer network. It is used as a path way for the exchange of data and information among interconnected computers and other devices. Transmission medium or communication medium is composed of communication channels which carry data in the form of data signals.
Types of transmission media: There are two main types of Transmission
media. Given below.
Cabling system or guided media
Wireless or unguided media
Cabling system or guided media: It is in the form of cables. It includes
Twisted pair cable
Fibre optic cables
Question 4 Answer.
Data encoding: The conversion of data from one form to another form is called data encoding.
There are two types of data encoding which are:
Data compression or packing
Question 5 Answer.
Modem: Modem stands for Modulator – Demodulator. It is an electronic device or card which performs modulation and demodulation. Modulation means to convert digital data into some other form such as analouge form so that it could be carried along the communication medium. Demodulation means to convert data from some other dorm such as analouge form back to digital form. So, Modem enables the transmission of digital
data over communication medium such as telephone line. A modem consists of two parts which are:
Receiving part or receiver: It performs demodulation and other functions.
Transmitting part or transmitter: It performs modulation and other
There are four types of modem which are:
Fiber Optic Modem
Question 6 Answer.
Transmission mode: The way of data transmission from sender to receiver is called transmission mode.
The way the sender and receiver communicate with each other is called transmission mode.
On the basis of interval in the process of data transmission and the number of characters to be transmitted. There are two types of transmission modes which are:
Asynchronous transmission mode
Synchronous transmission mode
Asynchronous transmission mode: It is also called start – stop transmission. In this transmission mode, a single character is transmitted at a time. Also there is no fixed time interval between two successive characters i-e characters are transmitted at irregular time intervals.
Synchronous transmission mode: This mode is more efficient than
Asynchronous transmission mode. In this mode, characters are grouped into blocks and a complete block of characters is transmitted at a time. There is no start bit and stop bit with each individual character, However there is a special character ‘sync’ character before each block. The ‘sysnc’ character show the begining of a block.
Question 7 Answer.
Types of transmission modes: On the basis of direction of data transmission
there are three modes.
Half Duplex transmission
Full Duplex transmission
Simplex transmission: It is one directional transmission in which the data is always transmitted from sender to receiver. Therefore, it is called one-way transmission.
Examples: Radio and Tv transmission.
Half Duplex transmission: It is a bi-directional transmission in which the data may be transmitted in boththe directions but in one direction at a time. Here, sender and receiver interchanged after some time.
Example: Walkie-talkie transmission.
Full Duplex transmission: It is also bi-directional transmission but here the data transmission may occur in both directions at the same time. Full Duplex transmission is more efficient than Half Duplex transmission because here the time is not wasted in switching the direction.
Example: Ordinary telephone communication.