BMW Young Academy
Basic Electrics
& Electronics
Lesson 1:
Basic Electrical Theory
Teacher Workbook
Jointly funded by the Quality Improvement
Agency and BMW (UK) Ltd
About Young Academy
Discover the skills needed to work in the automotive industry and learn about
the science and technology behind the cars with Young Academy, BMW
Education’s online resource for 14 to 16 year olds.
Young Academy is a series of online lessons based on BMW Academy’s
own award-winning apprenticeship programme. By working through the
lessons, you will take a journey from learning about the principles of electrical
theory, to developing an understanding of the skills and knowledge needed to
become a motor industry technician. The Young Academy lessons
incorporate the latest web-based training techniques, which enable you to
learn in the same way as the apprentices at the BMW Academy.
The Young Academy lessons are available from the BMW Education website
at: www.bmweducation.co.uk/YoungAcademy.
About Lesson 1: Basic Electrical Theory
This lesson introduces students to the principles of electricity. Students will
learn about the properties of electrons, how the movement of electrons
creates 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 move
through the pages using the ‘next’ or ‘previous’ navigation buttons at the
bottom 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 to
another 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 they
work through the lesson on the computer. The workbook can be used to make
notes and record answers to questions. The workbook is their personal record
of what they have learnt.
The teacher workbook contains the answers to the questions posed in the
student workbook.
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Finally…
The Young Academy lessons are the same lessons used by apprentices at
the BMW Academy, which is why you will come across references to
‘colleagues’ or other work-related words. Students should think of their
classmates as their colleagues and the classroom as their work place to get an
idea 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
Electron Flow
Page 14
Automotive Circuits
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Page 17
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Lesson 1: Basic Electrical Theory
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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Lesson 1: Basic Electrical Theory
Electrical Theory
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Lesson 1: Basic Electrical Theory
Atomic Structure
The basis for electricity is the electron. Electrons are extremely small particles
that are part of an atom. An atom is basically composed of electrons, protons
and neutrons.
Question 1: Please label the diagram below:
Answer:
Proton
Electron
Neutron
Nucleus
Each proton has one unit of positive charge and each electron has one unit of
negative charge. The atom is balanced (the number of electrons is the same
as the number of protons). A neutron, as its name suggests, has no charge.
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Lesson 1: Basic Electrical Theory
Ions
When the number of electrons equals the number of protons, the atom is
balanced 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 become
a positive ion.
Question 3: What would happen if electrons are added to an atom?
Answer: The atom would have a resultant negative charge and would
become a negative ion.
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Lesson 1: Basic Electrical Theory
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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Lesson 1: Basic Electrical Theory
Electrical Potential
The force exerted on groups of charged particles is called the electromotive force or
EMF.
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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Lesson 1: Basic Electrical Theory
Electron Displacement
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Lesson 1: Basic Electrical Theory
Static Electricity
Static electricity is the build-up of an electrical charge in an object. Static
electricity can sometimes suddenly discharge, for example, when a bolt of
lightning flashes through the sky. At other times, static electricity can cause
objects to cling to each other, like socks fresh out of the tumble dryer. The
static 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 to
another.
Friction is one way.
Rubbing a silk cloth over a glass rod causes electrons to move from the glass
rod 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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Lesson 1: Basic Electrical Theory
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 electrode
causing electrons to flow through the bulb to the positive electrode.
Electrolyte is normally a liquid solution (sulphuric acid and distilled water) that
enables a battery to supply electrical energy. Lead acid batteries have lead
plates immersed in this solution and a reaction takes place between these
lead 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 of
the electrode is changed through chemical action.
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Lesson 1: Basic Electrical Theory
Electrical Flow
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Lesson 1: Basic Electrical Theory
When the switch is closed on the circuit below, the circuit is completed or
‘closed’ and electrons flow through the wire – a flow of electric current is
taking place.
Question 11: What is the unit of current called?
Answer: The ampere or amp
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Lesson 1: Basic Electrical Theory
You will notice that the flow of electrons is from the negative electrode to the
positive electrode.
However, many people wrongly believe that current flows from the positive
terminal to the negative terminal.
Question 12: Please complete the sentence below:
This assumption is called the conventional flow and it incorrectly assumes that
the current flow will…
Answer: Flow from the positive to negative terminal.
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Lesson 1: Basic Electrical Theory
Automotive Circuits
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Lesson 1: Basic Electrical Theory
Diagrams
Question 13: Please label the components below:
Answer:
Bulb
Fuse
Switch
Battery
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Lesson 1: Basic Electrical Theory
Generally in automotive circuits, one side of the electrical component is
connected to the battery, whilst the other side is earthed (which means it is
connected to the ground).
Most vehicles use earth return systems where the metal body of the vehicle is
used as part of the circuit. The vehicle body is called the earth (or ground) and
is 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 the
feed and the other the return. By substituting the vehicle body for the return
cable, an earth return system is formed.
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Lesson 1: Basic Electrical Theory
Automotive Circuits
Resistance
Electrical resistance is the property of a given material that determines how
much current will flow when a given voltage is applied across it. Materials can
be classified into three categories depending on their electrical resistance
properties: 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 an
example:
Answer: Conductors have atoms that will easily give up electrons and will
produce current flow even with a small EMF. Copper, iron and aluminium are
good conductors.
Question 15: Describe what is meant by the term insulator and provide an
example:
Answer: Insulators have atoms that hold on tightly to their electrons. It takes
a large EMF to force any electron movement in insulators, thus the current
flow is small. Diamonds and glass are good insulators.
Question 16: Describe what is meant by the term semi-conductor and
provide an example:
Answer: Semiconductors are elements with unique atomic structures. By
combining semiconductors with other materials, the number of electrons
available to create current flows can be modified. Silicon and germanium are
semiconductors. Transistors are made from semiconductors.
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Lesson 1: Basic Electrical Theory
Assessment
Question 1: How many electrons would be needed to balance the electrical
charge 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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Lesson 1: Basic Electrical Theory
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 completed
Lesson 1: Basic Electrical Theory.
Please record your score in the box.
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