Electricity and electrical circuits final 20 maart
TECHNOLOGY ELECTRICITY AND ELECTRICAL CIRCUITS-BASIC CONCEPTS Liezel Oosthuizen 200932201
What is electricity?The flow of electrons inthe form of an electriccharge
What are the two types of electricity? a. Static electricity b. Current electricity
What is static electricity?When two objects rub against each other electronstransfer and build up on an object causing it to have adifferent charge from its surroundings.Like the shoes rubbing against the carpet. Electrons aretransferred from the carpet to the shoes.
As electrons collect on an object, it becomes negativelycharged. As electrons leave an object it attains a positivecharges. Charges interact with each other: Often when you remove clothes from the clothes dryer, they seem to stick together. This is because some of the clothes have gained electrons by rubbing against other clothes. The clothes losing electrons become positive. The negative clothes are attracted to the positive clothes.Have you ever rubbed a balloon on your hair andstuck it on a wall? How do you think this works?
What causes you to be shocked when you rub yourfeet across carpet?An electrical discharge is the passing of an electriccurrent through the air from a negatively charged objectto a positively charge object. This is what causeslightning!
What is current electricity? a. Negative charges that move along a path or wireHow is current electricity different from static electricity?a. Current electricity travels in a path made by a wireb. Static Electricity doesn’t travel in a path or wire
+ - battery junction wiring terminalvoltmeter V AC generatorammeter A Variable resistanceresistance Variable capacitorcapacitor
ELECTRIC CIRCUITS In an electric circuit, an energy source and an energy consuming device are connected by conducting wires through which electric charges move.
All electrical circuits require three elements. (1) A source voltage, that is, an electron pump usually a battery or power supply. [ ENERGY IN](2) A conductor to carry electrons from and to the voltage source (pump). The conductor is often a wire. [ENERGY TRANSFER](3) A load or resistance. A point where energy is extracted form the circuit in the form of heat, light, motion, etc. [ENERGY OUT]
High Resistance Low EnergyEnergy (Potential Drop) currentcurrent High Voltage Source Low Energy Energy (Potential Rise) current current
What are electric circuits?Circuits typically contain a voltage source, a wire conductor, andone or more devices which use the electrical energy.What is a series circuit?A series circuit is one which provides a single pathwayfor the current to flow. If the circuit breaks, all devicesusing the circuit will fail.
What is a parallel circuit?A parallel circuit has multiple pathways for the current toflow. If the circuit is broken the current may pass throughother pathways and other devices will continue to work.
RESISTANCEResistance (R) – is defined as the restriction of electron flow. It is due to interactions that occur at the atomic scale.For example, as electrons move through a conductor they are attracted to the protons on the nucleus of the conductor itself. This attraction doesn’t stop the electrons, just slow them down a bit and cause the system to waste energy. The unit for resistance is the OHM, W
Potential Current Resistance In volts In amperes In ohms(joules / coul) (coul / second) (volts / amp)Drop across a Current passing resistance Through the resistor
Electrical Calculations – What is Ohm’sLaw? 3V I= 2Ω I = 1.5 amps
How is Electrical Power calculated?Electrical Power is the product of the current (I) and thevoltage (v)The unit for electrical power is the same as that formechanical power in the previous module – the watt (W)Example Problem: How much power is used in acircuit which is 110 volts and has a current of 1.36amps?P=IVPower = (1.36 amps) (110 V) = 150 W
How is electrical energy determined?Electrical energy is a measure of the amount of powerused and the time of use.Electrical energy is the product of the power and thetime.Example problem: E = P X time P=IVP = (2A) (120 V) = 240 WE = (240 W) (4 h) = 960Wh = 0.96 kWh
REFERENCING Ch 20 Electric Circuits. (n.d.). Retrieved March 19, 2012, from http://www.slideshare.net/cscottthomas/ch-20-electric-circuits-online Electric circuits. (n.d.). Retrieved March 19, 2012, from http://www.slideshare.net/jmemler/electric-circuits-10520910 Electrical Circuits. (n.d.). Retrieved March 19, 2012, from http://www.slideshare.net/wsautter/electrical-circuits Electricity and Magnetism - Basic Concepts. (n.d.). Retrieved March 19, 2012, from http://www.slideshare.net/makadelhi/electricity-and-magnetism-basic-concepts Electricity.Electronics Ch20. (n.d.). Retrieved March 19, 2012, from http://www.slideshare.net/Wansyi/electricityelectronics-ch20-presentation Ohm’s law. (n.d.). Retrieved March 19, 2012, from http://www.slideshare.net/wathens/ohms-law- 7892325 chapter-12-lesson4-electricity-1216167849986490-8.ppt. (n.d.). Retrieved from http://s3.amazonaws.com/ppt-download/chapter-12-lesson4-electricity-1216167849986490- 8.ppt?response-content- disposition=attachment&Signature=2JTi69Np8a%2FhUaX0pWkNUl139K4%3D&Expires=1331653 554&AWSAccessKeyId=AKIAJLJT267DEGKZDHEQ