User talk:Abdulrahman Damboama Askira

POWER FACTOR
Power factor PF) is defined as a ratio between working power P (watts) and apparent power S (volt-amps):

PF = P/S = watts/Vrms×Irms

It is a quantity that tells us how effectively your device utilizes electricity. For an easy explanation of the physical meaning of PF, let's consider a simple example. Suppose you connect an ideal capacitor "C" across an AC line. Since AC voltage is continuously changing its polarity, half of the time the cap will be charging from the input and half of the time it will be returning the stored energy back to the source (see animation below). To view this animation you need to install Adobe Flash Player plug-in and allow blocked content

Courtesy of Joe Wolfe at Physclips Project at UNSW. As a result, certain current will be continuously circulating in the line, but there will be no net energy transfer. So, we will have both volts and amps, but not useful power. The volt-amp product "VA" is called apparent power because it is just a mathematical quantity which has no real physical meaning. Above is an example of a load with PF=0.

Similarly, a single ideal inductor will result in PF=0, except its current will lag the voltage. Let's now consider the opposite extreme case of a resistive load. In such a case, all the electric energy entering the load is consumed and converted to other forms of energy, such as heat. This is an example of PF=1. All real circuits operate somewhere between these two extremes.

In circuits analysis a sinewave signal can be represented by a complex number (called phasor) whose modulus is proportional to the magnitude of the signal and angle equals to its phase relative to some reference. In linear circuits PF= cosφ, where φ is angle between voltage and current phasors. These vectors and corresponding ones for active and reactive components of power can be presented by a triangle (see the diagram below). Of course, voltage is an electric field and current is a flow of electrons, so the so-called angle between their phasors is nothing more than another mathematical quantity. By convention, inductive load create positive volt-amp reactive (VARs). It is associated with so-called "lagging" power factor because current is behind the voltage. Abdulrahman Damboama Askira (talk) 04:52, 22 July 2017 (UTC)

TELECOMMUNICATION
Contact The DL Team Contact Us | Switch to single page view (no tabs) Abstract Authors References Cited By Index Terms Publication Reviews Comments This introductory book describes basic telecommunication technologies, the parts of public and private telephone systems, and how network elements operate. This book also provides fundamentals on almost all aspects of telecommunications. Covered are the key facets of voice and data communications, ranging from such basics as telephone devices to more complex topics such as voice over data networks. All of them are presented in a down-to-earth, easy-to-grasp manner with understandable illustrations. Some of the most important topics featured are: Analog and Digital Signal Processing Signal, Modulation, and Channel Coding Fundamentals Copper, Radio, and Optical Transmission Systems Circuit and Packet Switching Technologies Line and Trunk Signaling and Control Systems including SS7 Protocols, Stacks, and Parameter Negotiation ATM, Frame Relay, X.25, Internet, and other Networks PSTN, PBX, CTI, Mobile Telephone, and Satellite Systems Sending Voice over Data Networks Voice, Data, Video Services and Call Processing This book provides basic knowledge of telecommunications that is essential to anyone entering the field, changing job roles, or for executives who have been assigned to a position related to telecommunications. Abdulrahman Damboama Askira (talk) 04:56, 22 July 2017 (UTC)

ELECTRICITY
Electricity is a secondary energy source A hand unplugging an electrical appliance from an outlet Source: Stock photography (copyrighted)

Compact fluorescent light bulbs use about 25% of the electricity to produce the same amount of light as incandescent light bulbs. Energy efficient light bulb. Source: Stock photography (copyrighted)

Electricity is the flow of electrical power or charge. Electricity is both a basic part of nature and one of the most widely used forms of energy.

The electricity that we use is a secondary energy source because it is produced by converting primary sources of energy such as coal, natural gas, nuclear energy, solar energy, and wind energy into electrical power. It also referred to as an energy carrier, which means it can be converted to other forms of energy such as mechanical energy or heat. Primary energy sources are renewable or nonrenewable energy, but the electricity we use is neither renewable nor nonrenewable.

Electricity use has dramatically changed daily life Despite its great importance in daily life, few people probably stop to think about what life would be like without electricity. Like air and water, people tend to take electricity for granted. But people use electricity to do many jobs every day—from lighting, heating, and cooling homes to powering televisions and computers.

Before electricity became widely available about 100 years ago, candles, whale oil lamps, and kerosene lamps provided light, iceboxes kept food cold, and wood-burning or coal-burning stoves provided heat.

Scientists and inventors have worked to decipher the principles of electricity since the 1600s. Some notable accomplishments were made by Benjamin Franklin, Thomas Edison, and Nikola Tesla.

Benjamin Franklin demonstrated that lightning is electricity. Thomas Edison invented the first long-lasting incandescent light bulb. Abdulrahman Damboama Askira (talk) 04:59, 22 July 2017 (UTC)