What is 4G?

4G is the fourth generation of mobile phone technology and follows on from 2G and 3G.

2G technology was suitable for making calls and sending text messages while 3G makes it possible to access the internet more effectively through your mobile phone.

What to expect from 4G?

4G services should make it much quicker to surf the web on your mobile, tablets and laptops - speeds will be nearer to what you currently experience with home broadband.

Because of this, 4G is ideally suited for services which demand more capacity like video streaming, mapping and social networking sites.

For the typical user, download speeds of initial 4G networks could be around 5-7 times those for existing 3G networks.

This means a music album taking 20 minutes to download on a 3G phone and just over 3 minutes on 4G. This is based on existing 3G speeds being 1Mbit/s on average and 4G speed being 6Mbit/s (average of 5 and 7 times faster).

What will 4G coverage be like?

Ofcom has designed the 4G auction in a way that will see mobile broadband rolled out to at least 98% of people in villages, towns and cities across the UK. This is for indoor coverage; however, given that it is easier to provide coverage outdoors, a network meeting this obligation is likely to cover more than 99% of the UK by population when outdoors.

Ed Richards, Ofcom Chief Executive, said: 'As a direct result of the measures Ofcom is introducing, consumers will be able to surf the web stream high-quality videos and download big files on their mobile device from almost every home in the UK.'

What is Radiation

Radiation is energy that comes from a source and travels through space and may be able to penetrate various materials. Light, radio, and microwaves are types of radiation that are called nonionizing. The kind of radiation discussed in this document is called ionizing radiation because it can produce charged particles (ions) in matter.

Ionizing radiation is produced by unstable atoms. Unstable atoms differ from stable atoms because unstable atoms have an excess of energy or mass or both. Radiation can also be produced by high-voltage devices (e.g., x-ray machines).

Atoms with unstable nuclei are said to be radioactive. In order to reach stability, these atoms give off, or emit, the excess energy or mass. These emissions are called radiation. The kinds of radiation are electromagnetic (like light) and particulate (i.e., mass given off with the energy of motion). Gamma radiation and x rays are examples of electromagnetic radiation. Gamma radiation originates in the nucleus while x rays come from the electronic part of the atom. Beta and alpha radiation are examples of particulate radiation.

Interestingly, there is a "background" of natural radiation everywhere (ubiquitous) in our environment. Ubiquitous background radiation comes from space (i.e., cosmic rays) and from naturally occurring radioactive materials contained in the earth and in living things.

Radiation Exposure from Various Sources

Source	Exposure (U.S. Average)
External Background Radiation	0.54 mSv y-1
Natural K-40 and Other Radioactivity in Body	0.29 mSv y-1
Air Travel Round Trip (NY-LA)	0.05 mSv
Chest X-Ray Effective Dose	0.10 mSv per film
Radon in the Home	2.28 mSv y-1
Man-Made (medical x rays, etc.)	3.14 mSv y-1

Waht is Radio?

Radio is the radiation (wireless transmission) of electromagnetic energy through space.  The biggest use of radio waves is to carry information, such as sound, by systematically changing (modulating) some property of the radiated waves, such as their amplitude, frequency, phase, or pulse width. When radio waves strike an electrical conductor, the oscillating fields induce an alternating current in the conductor. The information in the waves can be extracted and transformed back into its original form.

Radio systems need a transmitter to modulate (change) some property of the energy produced to impress a signal on it, for example using amplitude modulation, angle modulation (which can be frequency modulation or phase modulation). Radio systems also need an antenna to convert electric currents into radio waves, and vice versa. An antenna can be used for both transmitting and receiving. Theelectrical resonance of tuned circuits in radios allow individual stations to be selected. The electromagnetic wave is intercepted by a tuned receiving antenna. A radio receiver receives its input from an antenna and converts it into a form usable for the consumer, such as sound, pictures, digital data, measurement values, navigational positions, etc. Radio frequencies occupy the range from a 3 kHz to 300 GHz, although commercially important uses of radio use only a small part of this spectrum.

A radio communication system sends signals by radio. The radio equipment involved in communication systems includes atransmitter and a receiver, each having an antenna and appropriate terminal equipment such as a microphone at the transmitter and aloudspeaker at the receiver in the case of a voice-communication system.

What is WiFy

Ans 1:

Wi-Fi (or WiFi) is a local area wireless computer networking technology that allows electronic devices to network, mainly using the 2.4 gigahertz (12 cm) UHF and 5 gigahertz (6 cm) SHF ISM radio bands.

The Wi-Fi Alliance defines Wi-Fi as any "wireless local area network" (WLAN) product based on the Institute of Electrical and Electronics Engineers' (IEEE) 802.11 standards". However, the term "Wi-Fi" is used in general English as a synonym for "WLAN" since most modern WLANs are based on these standards. "Wi-Fi" is a trademark of the Wi-Fi Alliance. The "Wi-Fi CERTIFIED" trademark can only be used by Wi-Fi products that successfully complete Wi-Fi Alliance interoperability certification testing.

Ans 2:

Wi-Fi is the name of a popular wireless networking technology that uses radio waves to provide wireless high-speed Internet and network connections. A common misconception is that the term Wi-Fi is short for "wireless fidelity," however this is not the case. Wi-Fi is simply a trademarked phrase that means IEEE 802.11x.

What is SIM?

A SIM card, also known as a subscriber identity module, is a smart card that stores data for GSM cellular telephone subscribers. Such data includes user identity, location and phone number, network authorization data, personal security keys, contact lists and stored text messages. Security features include authentication and encryption to protect data and prevent eavesdropping. A SIM card and can be switched easily from one phone set to another. The portability of data offers a number of benefits. For example, a user that buys a new phone can install the current SIM card to associate the new phone with the same number and user preferences as the old one. In another common situation, if a phone's battery runs out of power, the user can easily install the card to another subscriber's phone to borrow it without running up that user's minutes. Some vendors offer prepaid SIM cards that can provide travelers with local numbers, as long as their cell phones are not locked to a specific carrier. A device called a SIM card reader can be used to upload data from a SIM card to a computer or other device.

What is a computer virus?

Ans 1:
A computer virus is a malware program that, when executed, replicates by inserting copies of itself (possibly modified) into othercomputer programs, data files, or the boot sector of the hard drive; when this replication succeeds, the affected areas are then said to be "infected".  Viruses often perform some type of harmful activity on infected hosts, such as stealing hard disk space or CPU time, accessing private information, corrupting data, displaying political or humorous messages on the user's screen, spamming their contacts,logging their keystrokes, or even rendering the computer useless. However, not all viruses carry a destructive payload or attempt to hide themselves—the defining characteristic of viruses is that they are self-replicating computer programs which install themselves without user consent.

Ans 2:
A computer virus or worm is a self-replicating program that can spread by email or by inserting copies of itself into other programs or documents. Most viruses or worms aremalicious programs designed to infect and gain control over a computer without the owner’s knowledge.