BASIC DC ELECTRICITY

LESSON 1 – HOW DOES ELECTRICITY WORK? BASIC DC ELECTRICITY

Hydraulic system • OIL • Fuel System • FUEL • Electrical System? • Electrons WHAT IS OUR FLUID?

WHERE DO ELECTRONS COME FROM? • Electrons come from ATOMS • Atoms have two main parts • Nucleus • Protons (+ charge) • Neutrons (no charge) • Electrons (- charge) in orbit around the nucleus

ELECTRONS • The electrons in the outermost orbit of the atom are called VALENCE electrons • During electricity, or electrical flow, our “fluid” will be the VALENCE ELECTRONS that migrate from one atom to another • The inner electrons are magnetically bonded to the nucleus and therefore cannot move • The valence electrons have a weak bond that is easily broken to allow movement (flow)

DIFFERENT MATTER = DIFFERENT ATOMS Oxygen Chlorine Titanium Silicon

Allow easy flow of electrons from atom to atom • Have less than four valence electrons • 1, 2, or 3 CONDUCTORS Copper (1) Silver (1) Iron (2) Aluminum (3)

Inhibit electron flow (requires much more force) Have more than four valence electrons INSULATORS Argon (8) Nitrogen (5) Iodine (7) Sulfur (6)

Have EXACTLY four valence electrons SEMI-CONDUCTORS Carbon Silicon Germanium

Can be used as either a conductor or insulator depending on the application Diodes are primarily made up of semi-conductors SEMI-CONDUCTORS No Flow Flow

Usually made up of copper strands • Can also be other conducting material (aluminum, titanium, steel, etc.) • Each strand contains billions of atoms • Electricity is the flow of electrons from one atom to another atom in a conductor ELECTRICAL WIRE

VIDEO If the video does not automatically start by itself, do one of the two suggestions below. Click on the direct link to the video. Click here Go to www.youtube.com, copy / paste this code into the search box vL2KklctxQ0, and click on the video link that pops up.

Return to the course material listed in the LESSON 1 folder and click on the link labeled “Knowledge Check 1” This quiz will not be counted towards your final course grade but will provide valuable feedback before you move on After completing the knowledge check, return to this lesson and resume at slide #13 KNOWLEDGE CHECK

BASIC PARTS OF A CIRCUIT + - • Power source • Battery • Generator • Alternator • Provides a potential difference in magnetic charges between the two sides of the power source • Often called the VOLTAGE SUPPLY

BASIC PARTS OF A CIRCUIT • Conductor • Provides a path for electrons to travel between the positive and negative charged sides of the source

BASIC PARTS OF A CIRCUIT load • Load • Whatever electrical component you are trying to get work or power out of • Light bulb • Electrical motor • Solenoid valve • Provides resistance in the circuit which limits how many electrons can flow • Unlimited electron flow, or no resistance or no load, is bad • Balances the magnetic difference in the source (making it useless) • Creates tremendous heat from billions of electrons colliding with each other • Is dangerous because it can cause sparks and fire load

What happens when electrons are allowed to flow unlimited from one end of the source to the other Short circuiting If the video does not automatically start by itself, do one of the two suggestions below. Click on the direct link to the video. Click here Go to www.youtube.com, copy / paste this code into the search box lhVTDWjwY and click on the video link that pops up. You can fast forward to the 1:34 mark and play it until the 3:00 mark.

BASIC CIRCUIT SYMBOLS + Wire (conductor) - Battery (source) Resistance (load)

BASIC CIRCUIT DIAGRAM + -

Refers to the conducting side between the + charge of the source and the load POWER Power + -

Refers to the conducting side between the load and the - charge of the source GROUND + - Ground

WHY DO WE CALL IT “GROUND”? • In A/C electricity (alternating current), like in your home or on a farm, the actual earth (ground) plays a role in how the “return” side of the system works

WHY DO WE CALL IT “GROUND”? • The term has carried over to D/C electricity (direct current) and is used more as slang or jargon. • The earth plays no role at all in DC electricity • We say “ground” to simply identify the return side of the system

WHY DO WE CALL IT “GROUND”? • There are similarities • The ground in AC uses the earth as a return conductor instead of a wire • The ground in DC often uses the iron frame of the machine as a return conductor instead of a wire

WHY DO WE CALL IT “GROUND”? • There are similarities • The ground in AC uses the earth as a return conductor instead of a wire • The ground in DC often uses the iron frame of the machine as a return conductor instead of a wire Iron frame of machine Load Load Load Circuit “ground” point

Usually a switch of some type to activate or deactivate the circuit • Mechanical switch • Electrical switch (relay) • Solid state electronic switch (computer controller) control + -

The control can be placed on either side of the circuit • It can switch the power on and off control + -

The control can be placed on either side of the circuit • It can switch the power on and off • It can switch the ground on and off • In A/C electricity this is a safety hazard and is illegal. In D/C electricity it is perfectly normal and acceptable. control + -

Electrons are allowed to flow through the circuit from one side of the source to the other, including through the load which will allow it to work. CLOSED CIRCUIT + -

All electron flow is stopped everywhere in the circuit, including the load. The load will not work. OPEN CIRCUIT + -

The magnetic charged particles are still present. They just can’t flow OPEN CIRCUIT + + + + + + + + - - - - + + +

This diagram shows Conventional Flow Theory • Electrical flow starts at the positive terminal of the source and flows through the system returning to the source at the negative terminal WHICH WAY DOES IT FLOW? + -

This diagram shows Electron Flow Theory • Electrical flow starts at the negative terminal of the source and flows through the system returning to the source at the positive terminal WHICH WAY DOES IT FLOW? + -

Technically? • Electron Flow Theory • Electrons are negative charged particles and therefore should REPEL away from the negative terminal and ATTRACT towards the positive terminal Which way is correct? + -

Realistically for troubleshooting? • Conventional Flow Theory • Our primary tool for troubleshooting is a voltmeter • Voltmeters measure the difference in magnetic charge between two points in the system, often times referred to as the charge “gap” • The GAP direction is opposite the direction of the electrons Which way is correct? + 12.52 V -

GAP THEORY • Why it makes sense to troubleshoot electrical systems from positive to negative (conventional flow), even though the electrons flow from negative to positive If the video does not automatically start by itself, do one of the two suggestions below. Click on the direct link to the video. Click here Go to www.youtube.com, copy / paste this code into the search box 5igHrRV16uk and click on the video link that pops up.

Return to the course material listed in the LESSON 1 folder and click on the link labeled “Knowledge Check 2” This quiz will not be counted towards your final course grade but will provide valuable feedback before you move on After completing the knowledge check, return to this lesson and resume at slide #37 KNOWLEDGE CHECK

At this point you should be able to describe the “fluid” used in electrical systems, identify materials that make good conductors, good insulators, and good semi-conductors, and describe the path of electron flow through a complete circuit. You will soon take a lesson assessment that will be scored and recorded. You must achieve a minimum of 80% for each lesson in this course to receive credit. Are you ready? LESSON wrap up

One last review before the test LESSON wrap up If the video does not automatically start by itself, do one of the two suggestions below. Click on the direct link to the video. Click here Go to www.youtube.com, copy / paste this code into the search box D2monVkCkX4 and click on the video link that pops up. The video is over 8 minutes long but only the first 5:00 minutes is relevant for this lesson.

The links on the next page will take you to various web sites and videos with related information. You are not required to study them but may find them helpful if you are unsure about anything or just want more information. Additional resources

http://science.howstuffworks.com/electricity2.htm http://www.energyquest.ca.gov/story/chapter02.html http://www.qrg.northwestern.edu/projects/vss/docs/power/2-whats-electron-flow.html http://www.youtube.com/watch?v=EJeAuQ7pkpc http://www.youtube.com/watch?v=jbi7gJTPSXk http://www.youtube.com/watch?v=vL2KklctxQ0 http://science.howstuffworks.com/environmental/energy/circuit2.htm http://www.allaboutcircuits.com/vol_1/chpt_1/5.html http://www.allaboutcircuits.com/videos/16.html http://www.youtube.com/watch?v=ymRwIUNlEL4 http://www.engineeringinteract.org/resources/siliconspies/flash/concepts/buildingcircuits.htm http://tymkrs.tumblr.com/post/5513058883/conventional-flow-vs-electron-flow-theory http://www.allaboutcircuits.com/vol_1/chpt_1/7.html http://www.rare-earth-magnets.com/t-conventional-vs-electron-flow.aspx http://www.youtube.com/watch?v=5igHrRV16uk Additional resources

Return to the Lesson 1 folder and click on the link labeled “Lesson 1 Assessment.” It is required to have a minimum score of 80% for all lesson assessments to receive credit for completing this course. You may take the assessment as many times as needed to achieve a minimum score of 80% LESSON ASSESSMENT

AhmadSherif (Own work) [Public domain], via Wikimedia Commons Andy Dingley (Own work) [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons Djanes (Own work) [Public domain], via Wikimedia Commons Greg Robson) [CC-BY-SA-2.0-uk (http://creativecommons.org/licenses/by-sa/2.0/uk/deed.en)], via Wikimedia Commons Hight, S. (2012). Electron flow vs conventional current[Web]. Retrieved from http://www.youtube.com/watch?v=5igHrRV16uk Quarked Project. (2011). How electrons become electricity [Web]. Retrieved from http://www.youtube.com/watch?v=vL2KklctxQ0 Robinsonsauto. (2012). Having fun with fuses (short circuit)[Web]. Retrieved from http://www.youtube.com/watch?v=V-lhVTDWjwY Science Online. (2008). Electricity and circuits [Web]. Retrieved from http://www.youtube.com/watch?v=D2monVkCkX4 Scott Ehardt (Own work) [Public domain], via Wikimedia Commons Scratch (http://wiki.scratch.mit.edu/wiki/Category:Images) [CC-BY-SA-2.0 (http://creativecommons.org/licenses/by-sa/2.0) or CC-BY-SA-2.0 (http://creativecommons.org/licenses/by-sa/2.0)], via Wikimedia Commons StromBer 16:51, 17. Dez. 2007 (CET).StromBer at de.wikipedia [CC-BY-SA-2.0-de (http://creativecommons.org/licenses/by-sa/2.0/de/deed.en)], from Wikimedia Commons wdwd (Own work) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons Image and video attributions

BASIC DC ELECTRICITY