BASIC ELECTRICITY.pptx

Electricity

1. Basic electricity

2. Electricity is the flow of electrons from one place to another. Electrons can flow through any material, but does so more easily in some than in others. How easily it flows is called resistance. The resistance of a material is measured in Ohms. Electricity

3. Matter can be broken down into: Conductors:  electrons flow easily. Low resistance. Semi-conductors:  electron can be made to flow under certain circumstances. Variable resistance according to formulation and circuit conditions. Insulator:  electrons flow with great difficulty. High resistance.

4. Since electrons are very small, as a practical matter they are usually measured in very large numbers. A Coulomb is 6.24 x 10 18  electrons. However, electricians are mostly interested in electrons in motion. The flow of electrons is called current, and is measured in AMPS.  One amp is equal to a flow of one coulomb per second  through a wire.

5. Making electrons flow through a resistance requires an attractive force to pull them. This force, called Electro-Motive Force or EMF, is measured in  volts . A Volt is the force required to push 1 Amp through 1 Ohm of resistance.

6. As electrons flow through a resistance, it performs a certain amount of work. It may be in the form of heat or a magnetic field or motion, but it does something. This work is called Power, and is measured in Watts. One Watt is equal to the work performed by 1 Amp pushed by 1 Volt through a resistance.

7. NOTE: AMPS  is amount of electricity. VOLTS  is the Push, not the amount. OHMS  slows the flow. WATTS  is how much gets done.

8. There are 2 standard formulae that describe these relationships. Ohm's Law:  Where R = Resistance (ohms) E or V = Electro-motive Force (volts) I = Intensity of Current (amps)

9. Ohm's Law:  

10. To express work done:  Power formula (PIE Law): Where: P = Power (watts) I = Intensity of Current (amps) E = Electro-motive Force (volts) P = IE

11. This law is often restated in the units of measure as the West Virginia Law: W = VA for Watts = Volts x Amps

12. All this is important because all electrical equipment has a limit to how much electricity it can handle safely, and you must keep track of load and capacities to prevent failure, damage, or a fire. For example, a lamp is rated at 1000 w. @ 120 v. That means that at 120 volts it will use: 1000 w. / 120 v. = 8.33 a.

13. Types of E lectricity AC - ALTERNATING CURRENT DC – DIRECT CURRENT

14. Types of E lectricity AC - ALTERNATING CURRENT DC – DIRECT CURRENT

15. ALTERNATING CURRENT Alternating current or AC electricity is the type of electricity commonly used in homes and businesses throughout the world.

16. While the flow of electrons through a wire in direct current (DC) electricity is continuous in one direction, the current in AC electricity alternates in direction. The back-and-forth motion occurs between 50 and 60 times per second, depending on the electrical system of the country. ALTERNATING CURRENT

17. AC is created by an AC electric generator, which determines the frequency. What is special about AC electricity is that the voltage in can be readily changed, thus making it more suitable for long-distance transmission than DC electricity. ALTERNATING CURRENT

18. ALTERNATING CURRENT SOURCE

19. In a direct-current system, it's easy to determine voltage because it is nonvarying or varies slowly over time. You can simply make a measurement with a DC voltmeter. But in an AC circuit, the voltage is constantly changing. DIRECT CURRENT

20. In a direct-current system, it's easy to determine voltage because it is nonvarying or varies slowly over time. You can simply make a measurement with a DC voltmeter. But in an AC circuit, the voltage is constantly changing. DIRECT CURRENT

21. DIRECT CURRENT ALTERNATING CURRENT

22. Six ways to generate electricity Some are more widely used than others. Some are used just for specific applications.

23. Six ways to generate electricity Some are more widely used than others. Some are used just for specific applications. FRICTION — Voltage is produced when you rub certain materials together, like a balloon on your sweater. This was the first kind of electricity humans recognized. A Van de Graaff generator produces millions of volts with friction. It is not a very practical way to generate useful voltage—right after the big ZAP!ZAP!ZAP! the voltage disappears.

24. Six ways to generate electricity Some are more widely used than others. Some are used just for specific applications. PRESSURE (piezoelectricity) — Voltage produced by squeezing crystals of certain substances like quartz or tourmaline. Pronounced “pee-ay’- zoe ”. The microphone in a mobile phone is sensitive to sound pressure because it is made with a piezoelectric alloy called PZT, lead zirconate titanate.

25. Six ways to generate electricity Some are more widely used than others. Some are used just for specific applications. HEAT (thermoelectricity) — Voltage is produced by heating the junction between two different metals that have been welded together. This device is called a thermocouple . It is used to sense temperature. The schematic symbol looks like this,

26. Six ways to generate electricity Some are more widely used than others. Some are used just for specific applications. LIGHT (photoelectricity) — Voltage is produced when light hits a photosensitive (light sensitive) substance. Semiconductor materials like silicon are light sensitive. A photodiode is in a package with a window on top to allow light to hit the diode. The amount of light changes the conductivity of the diode.

27. Six ways to generate electricity Some are more widely used than others. Some are used just for specific applications. CHEMICAL — Voltage can be created by a chemical reaction. We call this a battery. Chemical action generates voltages inside your nerve cells.

28. Six ways to generate electricity Some are more widely used than others. Some are used just for specific applications. MAGNETISM — Voltage produced when the wire moves through a magnetic field, or a magnetic field moves past a conductor. This is how AC electricity is created in large-scale power plants, hydroelectric dams, and portable/emergency generators.

29. Types of power plants for energy generation

30. 1. Nuclear power plants

31. 1. Nuclear power plants Using a nuclear fission reaction and uranium as fuel, nuclear power plants generate a high amount of electricity. As  nuclear power plants  are considered to be a low-carbon energy source, the technology is widely thought of as a more environmentally-friendly option.

32. 1. Nuclear power plants When compared to renewable sources of energy such as solar and wind, the power generation from nuclear power plants is also considered to be more reliable. Although the investment required to bring a nuclear power plant online is significant, the costs involved in operating them are relatively low.

33. 1. Nuclear power plants Nuclear energy sources also have a higher density than fossil fuels and release large amounts of energy. Due to this, nuclear power plants require low quantities of fuel but produce a vast amount of power, making them particularly efficient once they are up and running.

34. 2 . Nuclear power plants Nuclear energy sources also have a higher density than fossil fuels and release large amounts of energy. Due to this, nuclear power plants require low quantities of fuel but produce a vast amount of power, making them particularly efficient once they are up and running.