Some definitions of Physics II

Flywheel:
A flywheel is a mechanical device with a significant moment of inertia used as a storage device for rotational energy.

Moment of Inertia:
The tendency of a body to resist angular acceleration.

Rotational Energy:
The rotational energy or angular kinetic energy is the kinetic energy due to the rotation of an object and is part of its total kinetic energy.
 
Revolution:
A revolution (from the Latin revolutio, "a turn around") is a fundamental change in power or organizational structures that takes place in a relatively short period of time.

Vanier Constant:
The long scale which you see on the vernier calliper is the main scale. It gives you the main reading but for the accurate value we also use the small vernier scale built on the movable arm.first you put cylinder in the jaws of vernier calliper .you have to take reading from the main scale and then you have to choose the best coinciding line(main scale wihh vernier scale) and multiplying that line no. with vernier constant which is 0.01 and then adding this value to the main scale reading you get your accurate reading.

Angular Acceleration:
Angular acceleration is the rate of change of angular velocity over time. In SI units, it is measured in radians per second squared (rad/s2), and is usually denoted by the Greek letter alpha (α)

Refractive index:
The refractive index (or index of refraction) of a medium is a measure of how much the velocity of a wave is reduced inside that medium.

Angular velocity:
In physics, the angular velocity is a vector quantity (more precisely, a pseudovector) which specifies the angular speed of an object and the axis about which the object is rotating. The SI unit of angular velocity is radians per second

Focal distance: 
The distance from a lens to its focus.

Spiro meter: 
A measuring instrument for measuring the vital capacity of the lungs

Shunt:
In electronics, a shunt is a device which allows electric current to pass around another point in the circuit. The term is also widely used in photovoltaics to describe an unwanted short circuit between the front and back surface contacts of a solar cell, usually caused by water damage.

Galvanometer:
meter for detecting or comparing or measuring small electric currents

Ammeter:
An ammeter is a measuring instrument used to measure the electric current in a circuit. Electric currents are measured in amperes (A)

Commutator:
Switch for reversing the direction of an electric current.

DC power Supply:
A power unit that supplies direct current only. Examples: battery, transformer / rectifier / filter circuit, DC generator, and photovoltaic cell.

 
Deflection:
In physics deflection is the event where an object collides and bounces against a plane surface.

Converging lens:
Lens such that a beam of light passing through it is brought to a point or focus

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More Abbreviation that related to Computer

Word	Abbreviation
W3C	World Wide Web Consortium
WWW	World Wide Web
VSAT	Very Small Aperture Terminal
VHS	Video Home System
VGA	Video Graphics Adapter
AGP	Advanced Graphics Port
UMTS	Universal Mobile Telecommunication System
TTF	True Type Font
GSM	Global System for Mobile
CDMA	Code Division Multiple Access
TDMA	Time Division Multiple Access
FDMA	Frequency Division Multiple Access
WCDMA	Wide Code Division Multiple Access
UHF	Ultra High Frequency
VHF	Very High Frequency
SONET	Synchronous Optical NETwork
SNR	Signal to Noise Ratio
RGB	Red Green Blue
RMS	Root Mean Square
SCSI	Small Computer System Interface
PIN	Personal Identification Number
PDF	Portable Document Format
GEO	Geostationary Earth Orbit
MEO	Medium Earth Orbit
LEO	Lower Earth Orbit
SEA-ME-WE	South EAst-Middle East-Western Europe
LED	Light Emitting Diode
LCD	Liquid Crystal Display
CRT	Cathode Ray Tube
LASER	Light Amplification by Stimulated Emission of Radiation
NMR	Nuclear Magnetic Resonance
MRI	Magnetic Resonance Imaging
OCR	Optical Character Recognition
OMR	Optical Mark Recognition

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Electro Magnetic Waves and its uses

Longitudinal waves:

Longitudinal waves are waves that have the same direction of vibration as their direction of travel, which means that the movement of the medium is in the same direction as or the opposite direction to the motion of the wave.

Example: Sound waves.

Transverse waves:

A transverse wave is a moving wave that consists of oscillations occurring perpendicular to the direction of energy transfer. If a transverse wave is moving in the positive x-direction, its oscillations are in up and down directions that lie in the y-z plane.

Example: Electromagnetic waves.

Electromagnetic waves:

Produced by the movement of electrically charged particles and it can travel in a “vacuum” (they do NOT need a medium) at the speed of light. It is also known as EM waves.

Photon:

A particle of light is called Photon.

Electromagnetic Spectrum:

The entire frequency range of electromagnetic waves is called Electromagnetic Spectrum.

Microwaves:

A short electromagnetic wave (longer than infrared but shorter than radio waves);  used for radar and microwave ovens and for transmitting telephone, facsimile, video and data.

Uses:

·         Microwave ovens

·         Bluetooth headsets

·         Broadband Wireless Internet

·         Radar

·         GPS

Inferred Radiation:

Wavelengths in between microwaves and visible light are called Inferred Radiation.

Uses:

·         Night vision goggles

·         Remote controls

·         Heat-seeking missiles

Visible light:

This is the only type of EM wave able to be detected by the human eye. Violet is the highest frequency light. Red light is the lowest frequency light

Ultraviolet:

Radiation lying in the ultraviolet range; wave lengths shorter than light but longer than x rays

Uses:

·         Black lights

·         Sterilizing medical equipment

·         Security images on money

X-rays:

Tiny wavelength, high energy waves.

Uses:

·         Medical imaging

·         Airport security

Gamma Rays:

Smallest wavelengths, highest energy EM waves

Uses: 

•      Cancer treatment

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Structure of a GSM System

We can divide GSM System into four components and they are:

·         Mobile Station

·         Base Station Subsystem

·         GPRS Core Network

·         Network Switching Subsystem

Mobile Station:

The mobile station (MS) comprises all user equipment and software needed for communication with a Wireless telephone network.

Terminal Equipment:

A device or devices connected to a network or other communications system used to receive or transmit data. It usually includes some type of I/O device.

SIM:

A smart card inserted into GSM telephones that contains the user's telephone account information, and that allows the user to use a borrowed or rented GSM telephone as if it were his or her own.

Base station subsystem:

The base station subsystem (BSS) is the section of a traditional cellular telephone network which is responsible for handling traffic and signaling between a mobile phone and the network switching subsystem.

BTS:

A base transceiver station (BTS) or cell site is a piece of equipment that facilitates wireless communication between user equipment (UE) and a network. UEs are devices like mobile phones (handsets), WLL phones, computers with wireless internet connectivity, Wi-Fi and Wi-MAX gadgets etc.

PCU:

The Packet Control Unit (PCU) is a late addition to the GSM standard. It performs some of the processing tasks of the Base Station Controller (BSC), but for packet data.

GPRS Core Network:

The General Packet Radio Service (GPRS) system is used by GSM mobile phones, the most common mobile phone system in the world, for transmitting IP packets. The GPRS core network is the centralized part of the GPRS system. It also provides support for WCDMA based 3G networks

SGSN:

A serving GPRS support node (SGSN) is responsible for the delivery of data packets from and to the mobile stations within its geographical service area.

GGSN:

A network node that acts as a gateway between a GPRS wireless data network and other networks such as the Internet or private networks. GPRS - General Packet Radio Service.  An enhancement to the GSM mobile communications system that supports data packets.

Network Switching System:

Network switching subsystem (NSS) (or GSM core network) is the component of a GSM system that carries out call switching and mobility management functions for mobile phones roaming on the network of base stations. It is owned and deployed by mobile phone operators and allows mobile devices to communicate with each other and telephones in the wider Public Switched Telephone Network or (PSTN).

MSC:

Mobile Switching Center (MSC) is the place that provides telephony switching services and controls calls between telephone and data systems. The MSC switches all calls between the mobile and the PSTN and other mobiles.

VLR:

Visitor Location Register (VLR) is a database - part of the GSM mobile phone system - which stores information about all the mobiles that are currently under the jurisdiction of the MSC (Mobile Switching Center) which it serves.

HLR:

A database containing subscriber information files about the subscriber and the current location of a subscriber's mobile station is called home location register.

EIR:

The GSM equipment identity register (EIR) database contains information on the identity of mobile equipment to prevent calls from stolen, unauthorized or defective mobile stations.

PSTN:

The public switched telephone network (PSTN) also referred to as the plain old telephone service (POTS) is the network of the world's public circuit-switched telephone networks. It consists of telephone lines, fiber optic cables, microwave transmission links, cellular networks, communications satellites, and undersea telephone cables all inter-connected by switching centers which allows any telephone in the world to communicate with any other.

BSC:

A device (or software) that controls the BTS’s within a GSM network. Within Private Mobile Networks one BSC can control and manage the signaling and voice channels for 100 BTS’s.

Abis: The Interface between base station and BSC is called Abis.

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