Answers of Chapter 9 "Discovering Computers 2011 : Living in a Digital World"

True/False
1. True
2. False
3. True
4. False
5. True
6. True
7. False
8. True
9.  True
10. True


Multiple Choice
1.c
2.c
3.c
4.c
5.b
6.a
7.d
8.b

Matching
1.e
2.j
3.h
4.d
5.f
6.a
7.g
8.b
9.c
10.i

Short Answers
1. Text messaging allows users to send and receive short text messages, typically fewer than 300 characters, on a phone or other mobile device or computer.
Options for text messaging :
• Mobile to Mobile: send a message from your mobile device to another mobile device
• Mobile to E-Mail: send a message from your mobile device to an e-mail address
• Web to Mobile: send a message from a text messaging Web site to a mobile device, or request that a Web site alert a mobile device with messages of breaking news and other updates
• Mobile to Provider: send a message by entering a common short code (CSC), which is a four- or five-digit number assigned to a specific content or wireless service provider, followed by the message, such as a vote for a television program contestant or an entry for a sweepstakes.

2. GPS satellites orbit Earth. Every thousandth of a second, each satellite sends a signal that indicates its current position to the GPS receiver, which determines its location on Earth by analyzing at least 3 separate satellite signals from the 24 satellites in orbit.
Individuals use the GPS in their mobile phone, vehicle, or may be to know their children's location, so they put the receiver on the children's bag, etc.

3. A local area network (LAN) is a network that connects computers and devices in a limited geographical area such as a home, school computer laboratory, office building. A metropolitan area network (MAN) is
a high-speed network that connects local area networks in a city or town and handles the bulk of communications activity across that region. A wide area network (WAN) is a network that covers a large geographic area (such as a city, country, or the world) using a communications channel that combines many types of media such as telephone lines, cables, and radio waves.

A wireless LAN (WLAN) is a LAN that is wireless.


4. A network topology refers to the layout of the computers and devices in a communications network. Five types of digital dedicated lines are ISDN lines, DSL, FTTP, T-carrier lines, and ATM.

5. Three types of digital modems are ISDN modems, DSL modems, and cable modems.

An ISDN modem sends digital data and information from a computer to an ISDN line and receives digital data and information from an ISDN line. A DSL modem sends digital data and information from a computer to a DSL line and receives digital data and information from a DSL line.A cable modem, sometimes called a
broadband modem, is a digital modem that sends and receives digital data over the cable television (CATV) network.