1. Automotive Electrics Course
Motor Vehicle Section
Automotive Electrics Course
Level 1

2. Morning Contents Day One Contents Atomic Structure Conductors (Copper)
Insulators (Plastics/Rubber)
Units of Electrical Measure
Current (Amps)
Voltage (Potential Difference & EMF)
Resistance (Ohm’s)
Power (Watts)
Basic Symbols and Circuits
Circuit Symbols
Series circuits and calculations
Parallel circuits and calculations

3. ELECTRONICS - The Basics
Atomic Structure
All matter is composed of substances called ‘ELEMENTS’. Elements are the purest and simplest substances and make up the ‘PERIODIC TABLE’, something that you may have heard mentioned in Chemistry lessons at school.
For example the Chemical make up of ‘WATER’ is given as H2O.
Two parts (Atoms) of Hydrogen combined with one part (Atom) of Oxygen. A Molecule of Water.

4. ELECTRONICS - The Basics
PERIODIC TABLE

5. ELECTRONICS - The Basics
Atomic Structure
electrons
nucleus
protons
neutrons

6. Positive ION
Negative ION

8. ELECTRONICS - The Basics
Atomic Structure
Neutrons do not carry an electrical charge, combine with protons, which are positively charged to make up the nuclei of all atoms, neutrons and protons do attract each other strongly when they are close together in the nucleus of an atom. However, electrons, which are negatively charged, are held much more weakly to atoms, and it is this weakness upon which electronics is based.

9. ELECTRONICS - The Basics
Atomic Structure
It is thought that Electrons orbit the nucleus of atoms in shells (like the planets orbiting the sun). In these shells there should be a specific number of electrons. The number of electrons in the shells will be dependant on the element/material in question, but the inner shells are always filled before the outer shells.
If an atom has a complete outer shell, then it is thought that the electrons are tightly bonded and the material will not conduct electricity very well (INSULATOR)

10. Please complete Exercise 1 in the assessment book
The above gives details of Coppers atomic structure, with a single electron in the outer shell, which can be passed from atom to atom. A GOOD CONDUCTOR.
Please complete Exercise 1 in the assessment book

11. Please complete Exercise 1 in the assessment book
The above gives details of Coppers atomic structure, with a single electron in the outer shell, which can be passed from atom to atom. A GOOD CONDUCTOR.
Please complete Exercise 1 in the assessment book

12. When a link is placed across a battery then the surplus electrons in the NEGATIVE end of the battery try to fill the ‘holes’ at the POSITIVE end of the battery
The Rate of Flow of Electrons from the negative side of the battery to the positive side of the battery is called
CURRENT FLOW

13. A battery when fully charged is filled with positive ions at one end and negative ions at the other

14. The difference in pressure causes electrons to flow, this potential difference is called
VOLTAGE
50 psi
50 psi
100 psi
0 psi

15. If a restriction is now put into the link this has the effect of reducing the electron(current) flow This is call a
RESISTOR
and is measured in
OHMS

16. To help understanding of the basic principles it often helps to use a WATER ANALAGY
Water pressure
Voltage (volts)
Water Flow
Current (amps)
Tap
Resistor (Ohms)
Turbine
Power (watts)

17. Lets now analyse this Statement
OHMS LAW (Ω)
G S Ohms in 1827 Stated that;
The current flowing through a metallic conductor at a constant temperature is proportional to the potential difference applied to its ends
Lets now analyse this Statement

18. The current flowing through a metallic conductor
The amount of current flow in a circuit,
measured in amps
Metallic conductor could be a length of copper wire

19. is proportional
When one goes up the other goes up, and when one goes down the other goes down

20. potential difference applied to its ends
The difference in electrical potential at either end - Voltage
Measured in volt

21. The current flowing through a metallic conductor at a constant temperature is proportional to the potential difference applied to its ends
If there is an increase in voltage then there will be a corresponding increase in current flowing
If there is an increase in resistance then there will be a corresponding decrease in current flowing

22. VOLTS = AMPS X RESISTANCE
therefore
VOLTS = AMPS X RESISTANCE OR
AMPS = VOLTS
RESISTANCE
RESISTANCE = VOLTS
AMPS

23. V = Voltage (Volts)
I = Current (Amps)
R = Resistance (Ohm’s) V R I

24. Please complete Exercise 2 in the Assessment book
Ohm’s Law Example
In a 24volt truck circuit, what would be the current flow through a 3Ω resistor?
8 A ‘s
Please complete Exercise 2 in the Assessment book

25. CIRCUITS

26. A circuit consists of A Supply such as a Battery,
A Component such as a Bulb,
A method of control such as a switch
And
Sufficient wiring to allow current to flow from one side of the battery to the other
A CIRCUIT PROTECTION DEVICE A FUSE

27. Circuit Symbols
To ensure repair personnel can attend to failures in electrical circuits. Components are given designated symbols for universal standardisation. The most common standards these days are IEC (International Electrotechnical Commission) or DIN (Deutsches Institut für Normung ). Which are replacing the old British Standard. Examples of some of these symbols will be discussed on the next few slides.

28. THE CURRENT HAS TO FLOW THROUGH EACH RESISTOR IN TURN
TYPES OF CIRCUIT
SERIES CIRCUIT
THE CURRENT HAS TO FLOW THROUGH EACH RESISTOR IN TURN

29. THE CURRENT SPLITS AND DIVIDES BETWEEN EACH BRANCH IN THE CIRCUIT
TYPES OF CIRCUIT
PARALLEL CIRCUIT
THE CURRENT SPLITS AND DIVIDES BETWEEN EACH BRANCH IN THE CIRCUIT

30. AN OPENING IN THE CIRCUIT
TYPES OF CIRCUIT
OPEN CIRCUIT
AN OPENING IN THE CIRCUIT
NO CURRENT CAN FLOW

31. NO OPENING IN THE CIRCUIT
TYPES OF CIRCUIT
CLOSED CIRCUIT
NO OPENING IN THE CIRCUIT
CURRENT WILL FLOW

32. EXCESSIVE CURRENT WILL FLOW
TYPES OF CIRCUIT
SHORT CIRCUIT
COMPONENT IS BYPASSED
EXCESSIVE CURRENT WILL FLOW

33. TYPES OF CIRCUIT SERIES CIRCUIT
Resistors are placed in a series (one after the other)
Current remains constant throughout the circuit
Voltage drops across each resistor

34. SERIES CIRCUIT RESISTOR VALUES
To find the total resistance, just add up the value of each resistor
R1 3Ω R3 5Ω R2 4Ω
RT = R1+R2+R3
RT = 3+4+5
RT = 12 Ω
Please complete exercise 3 in the assessment book.

35. PARALLEL CIRCUITS RESISTOR VALUES
In a parallel circuit the voltage will be constant and the current flow in each branch adds up to the total current flow.

36. PARALLEL CIRCUITS RESISTOR VALUES
There are two ways to calculate the resistance of a parallel circuit.
The easiest way is to work with only two resistance values at one time and apply the formula below.
RT = R1 X R2
R1 + R2

37. PARALLEL CIRCUITS RESISTOR VALUES
Calculate the total resistance of this circuit.

38. PARALLEL CIRCUITS RESISTOR VALUES

39. PARALLEL CIRCUITS RESISTOR VALUES
If there are more than two resistors, the resistance value of two at a time can be calculated and then put back into the formula.
Please follow the explanation from your tutor, for the following circuit.

40. PARALLEL CIRCUITS RESISTOR VALUES
Please complete exercise 4 in the assessment booklet.

41. How do we know how much work an electrical component is doing?
ELECTRICAL POWER
Power is the rate of doing work. This applies to electrical components as the energy stored in a battery can be converted to mechanical work in a motor (Power Dissipated).
How do we know how much work an electrical component is doing?

42. Electrical power is said to be the product of voltage and current.
Power can be calculated by using a formula, which is easy to use when a magic triangle is adopted as in Ohm’s Law.
Electrical power is said to be the product of voltage and current.
P = V x I

43. P = Power (Watts)
V = Voltage (Volts)
I = Current (Amps) P I V

44. Please complete exercise 5 in the assessment booklet.
How much power is dissipated in a circuit with a motor that is drawing 7 amps? Assume that the circuit is connected to a 24 volt supply.
P = I x V
P = 7 x 24
P = 168 watts
Please complete exercise 5 in the assessment booklet.