lesson 1 basic electrics teacher

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BMW Young Academy

Basic Electrics

& ElectronicsLesson 1:

Basic Electrical Theory

Teacher WorkbookJointly funded by the Quality ImprovementAgency and BMW (UK) Ltd


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About Young Academy

Discover the skills needed to work in the automotive industry and learn aboutthe science and technology behind the cars with Young Academy, BMWEducations online resource for 14 to 16 year olds.

Young Academy is a series of online lessons based on BMW Academysown award-winning apprenticeship programme. By working through thelessons, you will take a journey from learning about the principles of electricaltheory, to developing an understanding of the skills and knowledge needed tobecome a motor industry technician. The Young Academy lessonsincorporate the latest web-based training techniques, which enable you tolearn in the same way as the apprentices at the BMW Academy.

The Young Academy lessons are available from the BMW Education websiteat: www.bmweducation.co.uk/YoungAcademy.

About Lesson 1:Basic Electrical Theory

This lesson introduces students to the principles of electricity. Students willlearn about the properties of electrons, how the movement of electronscreates a flow of electricity and how electrical circuit boards function.

Working through the online lesson

The online lesson is divided into five sections:

- Introduction- Objectives- Content

- Assessment- Summary

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Students should work through each section in turn.

Once the lesson has been launched from the website, students can movethrough the pages using the next or previous navigation buttons at thebottom of the screen. There is also a replay button, for repeating any of the

activities or animations, and an exit button to end the lesson.

The menu at the top of the screen can be used to move from one section toanother without going through all the pages.

Lesson menu Navigation buttons

Clicking on the help button shows how to use the navigation in more detail.

Using the student workbook

Each lesson is accompanied by a workbook that students can fill in as theywork through the lesson on the computer. The workbook can be used to makenotes and record answers to questions. The workbook is their personal recordof what they have learnt.

The teacher workbook contains the answers to the questions posed in thestudent workbook.

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Finally

The Young Academy lessons are the same lessons used by apprentices atthe BMW Academy, which is why you will come across references tocolleagues or other work-related words. Students should think of their

classmates as their colleagues and the classroom as their workplace to get anidea of what being an apprentice is like!

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Lesson 1: Basic Electrical Theory

Overview

Objectives Page 5

Electron Theory Page 6

Electron Displacement Page 11

Electron Flow Page 14

Automotive Circuits Page 17

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Objectives

At the end of this lesson you should be able to:

Explain the basic structure of atoms

Explain the behaviour of ions

Explain why various types of materials have an effect on resistance

Explain the definitions of voltage and current resistance.

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Electrical Theory

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Atomic Structure

The basis for electricity is the electron. Electrons are extremely small particlesthat are part of an atom. An atom is basically composed of electrons, protonsand neutrons.

Question 1: Please label the diagram below:

Answer:

ElectronProton

Neutron

Nucleus

Each proton has one unit of positive charge and each electron has one unit ofnegative charge. The atom is balanced (the number of electrons is the sameas the number of protons). A neutron, as its name suggests, has no charge.

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Ions

When the number of electrons equals the number of protons, the atom isbalanced and there is no resultant charge.

Question 2: What would happen if electrons are taken away from an atom?

Answer: The atom would have a resultant positive charge and would becomea positive ion.

Question 3: What would happen if electrons are added to an atom?

Answer: The atom would have a resultant negative charge and wouldbecome a negative ion.

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Charged Particles

Question 4: Please tick the correct statement below:

Answer: Ions with UNLIKE charges attract.

Question 5: Please tick the correct statement below:

Answer: Ions with LIKE charges repel.

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Electrical Potential

The force exerted on groups of charged particles is called the electromotive force orEMF.

Question 6: What name is given to the measure of EMF?

Answer: Electromotive force

Question 7: What two terms are sometimes used instead of EMF?

Answer: Potential difference and voltage

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Electron Displacement

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Static Electricity

Static electricity is the build-up of an electrical charge in an object. Staticelectricity can sometimes suddenly discharge, for example, when a bolt oflightning flashes through the sky. At other times, static electricity can causeobjects to cling to each other, like socks fresh out of the tumble dryer. Thestatic cling is an attraction between two objects with different charges, positive(+) and negative (-). This can be caused by friction.

There are a number of ways that electrons can be moved from one material toanother.

Friction is one way.

Rubbing a silk cloth over a glass rod causes electrons to move from the glassrod to the cloth.

Question 8: When this happens, the glass rod becomes?

Answer: The rod becomes positively charged.

Question 9: .and the silk cloth becomes?

Answer: The cloth becomes negatively charged.

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Chemical Action

The chemical action of a battery is another way to displace electrons.

When the circuit is complete, the electrolyte reacts with the negative electrodecausing electrons to flow through the bulb to the positive electrode.

Electrolyte is normally a liquid solution (sulphuric acid and distilled water) thatenables a battery to supply electrical energy. Lead acid batteries have leadplates immersed in this solution and a reaction takes place between theselead plates and the solution when the battery is being discharged.

Question 10: Describe what happens to the electrolyte.

Answer: When the light is on the electrolyte turns to water and the material ofthe electrode is changed through chemical action.

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Electrical Flow

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You will notice that the flow of electrons is from the negative electrode to thepositive electrode.

However, many people wrongly believe that current flows from the positiveterminal to the negative terminal.

Question 12: Please complete the sentence below:

This assumption is called the conventional flow and it incorrectly assumes thatthe current flow will

Answer: Flow from the positive to negative terminal.

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Automotive Circuits

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Diagrams

Question 13: Please label the components below:

Answer:

Bulb

Battery

Switch

Fuse

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Generally in automotive circuits, one side of the electrical component is

connected to the battery, whilst the other side is earthed (which means it isconnected to the ground).

Most vehicles use earth return systems where the metal body of the vehicle isused as part of the circuit. The vehicle body is called the earth (or ground) andis normally connected to the negative side of the battery terminal.

The use of the word return is associated with the current flow in the circuit.When a lamp is connected to a battery by two cables, one cable is called thefeed and the other the return. By substituting the vehicle body for the return

cable, an earth return system is formed.

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Automotive Circuits

Resistance

Electrical resistance is the property of a given material that determines howmuch current will flow when a given voltage is applied across it. Materials canbe classified into three categories depending on their electrical resistanceproperties: conductor; insulator; or semi-conductor.

Current will flow through the materials or path with least resistance.

Question 14: Describe what is meant by the term conductor and provide anexample:

Answer: Conductors have atoms that will easily give up electrons and willproduce current flow even with a small EMF. Copper, iron and aluminium aregood conductors.

Question 15: Describe what is meant by the term insulator and provide anexample:

Answer: Insulators have atoms that hold on tightly to their electrons. It takesa large EMF to force any electron movement in insulators, thus the currentflow is small. Diamonds and glass are good insulators.

Question 16: Describe what is meant by the term semi-conductor andprovide an example:

Answer: Semiconductors are elements with unique atomic structures. Bycombining semiconductors with other materials, the number of electronsavailable to create current flows can be modified. Silicon and germanium aresemiconductors. Transistors are made from semiconductors.

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Assessment

Question 1: How many electrons would be needed to balance the electricalcharge of the nucleus?

Answer: 8 (oxygen atom)

Question 2: A battery is connected to each of the following materials.Which branch will the current flow through?

Answer: Copper Wire

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Question 3: Please draw a line to match the statements with the correct word.The first one has been completed for you as an example.

Answer:

Question 4: Materials that easily give up their electrons are called:

Answer: Conductors

Question 5: What is used instead of the term EMF?

Answer: The terms Potential Difference of voltage

Well done! You have now completedLesson 1: Basic Electrical Theory.

Please record your score in the box.

lesson 1 basic electrics teacher

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