Information Technology [2 Mark Questions]

Ravi could either of the two technologies Bluetooth or Infrared which is supported by both the devices involved. Infrared though slightly faster than Bluetooth has a limitation that it needs a clear line-of-sight between the devices for it to work.

Bluetooth technology is used for sharing the data like audio, video etc. Using this technology, users of cellular phones, initiate the sending or receiving data.
In general, having all mobiles and fixed computer devices can be totally coordinated. Thus, Mr. Singh and Mr. Tyagi can send a song to each other by using a bluetooth technology easily within short time.

Manoj would be setting up a PAN (Personal Area Network) which is best suited for setups involving a computer, a cell phone and/or a handheld computing device such as a PDA.

(i) computers
(ii) connected
(iii) communication
(iv) network
(v) share

MODEM performs the task of Modulation at sender’s site and DEModulation at the receiver’s end. Basically, our computer generates data in the form of digital signals which needs to be forwarded to the receiver through telephone lines. Since, telephone lines can carry only analog signals. So digital signals need to be converted to analog signals at sender’s site this is called modulation. At receiver’s end again analog signals should be converted back to the original digital signals, then this is called demodulation.

Differences between long distance and short distance wireless media are as follows:

Long distance wireless media	Short distance wireless media
It supports communication over a long distance, i.e. upto thousands of kilometres.	It supports communication over a short distance, i.e. upto few kilometres
Microwave, radiowave and satellite communication are long distance wireless media.	Bluetooth, infrared, wi-fi, WiMAX are short distance wireless media.

Bluetooth and Infrared both are short range wireless transmission media. This is the only point at which both these data transmission technologies look similar but there is a lot of difference between the two. Infrared is mostly used in TV remotes and there must be a direct line-of-sight between the transmitter and the receiver while on the other hand bluetooth uses a radio frequency which allows transmission through walls and other objects.

The three main parts of optical fibre cable are as follows:

• Core It is the section through which the data travel in the form of light.
• Cladding The cladding is the covering part of core. Its function is to reflect back the light into the core, as it is a denser medium.
• Protective Coating It is the outer cover of cladding for the protection of optical fibre from damage and moisture.

TWO problems that can occur during transmission of data are as follows:

• Crosstalk Disturbance caused by the electric or magnetic fields of one signal in an adjacent signal.
• Attenuation During transmission, the signal strength is reduced this phenomenon is called attenuation.

Twisting the cables keep them close together so that, any external magnetic fields must cross both cable at the same time, so the interference created in one cable is cancelled by the almost exact opposite amount of interference in the other.

Internet
Access by any individual with dial-up access.
Information on Internet could be general, public and advertisement.
Intranet
Access by only authorised employees.
Information on Intranet could be specific, corporate and proprietary.

TWO uses of Internet are as follows:

• Internet is used for communication and information sharing.
• Businesses use the Internet to provide access to complex databases.

LAN
A Local Area Network (LAN) is a computer network covering a small geographical area like a home, office or small group of buildings such as buildings in a school. Computers connected to a LAN can share information and share peripheral equipments.
WAN
A Wide Area Network (WAN) is used to connect LANs and other types of network together, so that users and computers in one location can communicate with users and computers in other locations.

Two major points of differences among LAN, MAN and WAN are as follows:

• Distance Covered LAN can cover an area upto 5 km. More than 5 km and upto 100 km comes under MAN. Beyond 100 km, the area can be covered by WAN only.
• Cost LAN has lower cost as compared to MAN and WAN.