Basics OfAutomotive Electrical & Electricity

Matter

• Anything that has mass & takes up space:

Matter

• Can exist in three states• Solids • Liquids• Gases

Molecule

• Smallest portion of matter that still retains all of the properties of the original

• Molecules are made up of atoms

The Atom

-

+ N

A n Atom is the smallest form of an element. Combining Atoms forms molecules that make up all matter. The term Electricity comes from the Greek word elektron, meaning: Amber. Amber is a fossil resin that Ancients rubbed with wool to produce static electricity. This was their way of “shocking” someone since they had no nylon carpet in their tents!

The Atom The word atom comes from the Greek

ἄτομος/átomos, α-τεμνω, which means uncuttable or something that cannot be divided further

They are a basic unit of matter They consist of a dense central nucleus surrounded by a cloud of negatively

charged electrons & electrically neutral neutrons

Atoms• 100 + different types• One molecule of water is made up of

one atom of oxygen, two atoms of hydrogen H20

All Atoms are made up of

Electrons Protons Neutrons

PARTS OF ATOMS 1. PROTON - part of nucleus, is positively charged

2. NEUTRON - part of nucleus that is neutral

(has a positive & negative charge)

3. ELECTRON - orbits the nucleus, is negatively charged

• An atom with more protons then electrons- is called a positive charged atomproton & neutron in center; electrons orbit

Bound electrons

• Are in the inner orbits • Since bound electrons are very close to the

center nucleus they have a strong magnetic attraction, they are very difficult to remove from their orbit

Free electrons

• Located in the outer orbit only, one, two or three electrons, they loosely bound & are easily knocked out of their orbit

The negatively charged electrons of an atom are bound to the positively charged nucleus by electromagnetic force

• An atom containing an equal number of protons & electrons is electrically neutral

• an atom has a positive or negative charge it is considered an ion

Atomic Structure Determines How An Atom Acts

Insulators will have 5 – 8 electrons in their outer orbit

Semi Conductors will have 4 electrons in their outer orbit

Conductors will have 1 - 3 electrons in their outer orbit1 conducts much better than 3

Conductors • Have 1-3 electrons in their outer orbit• Magnetic force is trying to pull them in closer &

centrifugal force is trying to move them further out & away from the positively charged center or nucleolus

• Since they are out in the outer orbit & the magnetic pull is weaker they are easily knocked out of their orbit

• Materials such as silver, copper, aluminum, gold make good conductors.

Semi-Conductors• 4 electrons in outer orbit

• Not a good conductor• Not a good insulator

Non conductors

• Insulators, 5 or more electrons in outer orbit, glass, ceramics, plastics, rubber, fiber, porcelain, paper & wood are common Insulators.

• These electrons are much more difficult to knock out of orbit, they have a stronger magnetic force to each other because they are closer together & to the positively charged protons in the nucleus or center of the atom

Different Elements

Each element has it’s own individual characteristics & each has a different number of electrons, protons, and neutrons circling the nucleus. No atom has more than eight electrons in the outer shell or valance ring. This is how we get different characteristics that are helpful in generating, conducting, & insulating electrical currents

Orbits

A Negative ion - is an atom that has gained one or more negatively charged electronsA Positive ion - is an atom that has lost one or more negatively charged electrons LAW FOR CHARGES (Just like magnets)

LIKE CHARGES REPEL UNLIKE CHARGES ATTRACT

Current flow begins when electrons in a circuit move

Conductors Conductors are materials with 1 to 3 electrons in the outer orbit

These electrons are loosely bound or not very close to the opposite or positively charged nucleus & they have a week magnetic attraction

This allows these electrons to be easily given up as free electrons & they jump to another atom causing current flow

Gold, Silver, & Copper are examples of a good conductors because they have only one electron in their outer orbit

Insulators Insulators are materials with 5 to 8 electrons in their outer orbit

Because they have more electrons in their outer orbit they are in closer proximity to each other

Because electrons are all negatively charged they repel each other & the electrons from other atoms thus they block or will not allow electrons to jump or join them

Plastic, rubber, & ceramics are examples of good insulators

Semiconductors

Semiconductors are neither conductors nor insulators.

Semiconductors are materials that contain exactly 4 electrons in the atom’s outer orbit & are, therefore, neither good conductors nor good insulators.

Silicone & germanium are examples of semiconductors

Conductor - has 1 to 3 outer orbit electrons

Insulator - has 5 to 8 outer orbit electrons

Semiconductor - has 4 outer orbit electrons

EXAMPLES

Gold - 1 outer orbit electronSilver - 1 Copper - 1Iron - 2 Aluminum - 3

PLASTIC RUBBER Silicon - 4

Germanium - 4

ECTROMOTIVE FORCE

EMF - is the electrical pressure or force that causes electrons to flow in a circuit. EMF is measured in volts VOLTAGE - The pressure necessary to cause electron movement.

6 WAYS TO PRODUCE VOLTAGE

1. FRICTION

2. CHEMICAL

3. HEAT

4. LIGHT

5. PRESSURE

6. MAGNETISM

Electrons (energy) in a potential or stored state, are static not moving electricityElectrons in a discharged state (flowing) become kinetic moving electricity

Electron movement in a circuit is called current flow

CURRENT FLOW- Is caused because of a voltage imbalance 2 differing voltage levels trying to get balanced 12 Volts on the positive side & 0 Volts on the negative side

Current flow is measured in amperes or amps. 1 Amp = 6,250,000,000,000,000,000 that’s 6.25 Billion Billion electrons per second passing a given point in a conductor

THEORIES OF CURRENT FLOW:

CONVENTIONAL – STATES THAT

CURRENT FLOWS FROM POSITIVE TO NEGATIVE Used in automotive wiring diagrams

ELECTRON – STATES THAT CURRENT FLOWS FROM NEGATIVE TO POSITIVE

RESISTANCE - is anything that limits the flow of electrons (current flow) in a circuit Resistance is measured in OHMS.

The resistance of an object is determined by :

1. The type or composition of the material.

2. The length of the material

3. The diameter of the material 4. The temperature of the material. Resistances can vary from allowing large amounts of current flow to allowing no current flow.

All materials including conductors have a certain amount of resistance

Zero resistance cannot be achieved at normal temperatures In most materials resistance is directly proportional totemperature

. As temperatures go up resistance goes up As temperatures go down resistance goes down

Ohms Law

1 volt of electrical pressure is required to push 1 amp of current through 1 ohm of resistance

Volts, Amps, & Ohms

Amps -Discovered & named after Frenchman: André Marie Ampere (1775-1836)

1. Unit of measurement for current flow.

2. A and amps are acceptable abbreviations for amperes.

3.The capital letter I is for intensity - used in mathematical calculations.

4. Amperes is measured using an Ammeter not an ampmeter

. Volts -Discovered and named after the Italian Scientist: Alessandro Volta (1745-1827)

1. Unit of measurement for electrical pressure.

2. Electromotive Force, EMF, is another way of indicating voltage.

3. The capital letter V is the acceptable abbreviation for volts.

4. The symbol used in calculations is the letter E, for EMF.

5. Voltage is measured using a Voltmeter.

Ohms -The German scientist Georg Simon Ohm (1787-1854) discovered the relationship between volts amps and resistance and produced Ohms Law.

1. Unit of measurement for electrical resistance.

2.The symbol for ohms is Ω the last letter of the Greek alphabet.

3.The symbol used in calculations is the letter R, for resistance.

4.Ohms are measured using an Ohmmeter.

A complete automotive circuit contains all of the following: 1. Power Source – usually the battery or alternator 2. Conductors - wires, cables, circuit boards, etc. 3. Circuit Protection – usually a fuse or fusible link 4. Load(s) - the electrical device(s) to be operated

5. Control Device - switch, relay, microprocessor

SOURCES OF ELECTRICAL ENERGY

Power Source

MAGNETIC

– Coils– Alternators

LIGHT

– Photo Cells

HEAT

– Thermocouples

PRESSURE

– Piezoelectric crystals Knock sensors

VOLTAGE

• Electrical pressure or potential

• Electromotive force causes the movement of electrons

• Electrical pressure is measured in volts

• Automotive electrical systems are considered 12 volt even though they are actually operate at higher voltages

VOLTAGE

• Potential• Pressure• Measured in Volts• V • Electromotive

Force• EMF • E

AMPERAGE

• The movement of electrons

from one atom to another

• Trying to create a balance

AMPERAGE

• The rate of electron flow

• Measure in amperes or amps

• If voltage goes up, current flow increases

• If voltage goes down, current flow decreases

AMPERAGE

• Flow of electrons• Current flow• Measured in Amps Ampere(s)• Amp(s) • A• Intensity• I

What does it take?• To make electrons or current flow, you must

have a complete or closed circuit including a return or ground side path back to the power source

• If more pressure (Volts) are applied more work can be done

• If more electrons (Amps) are moving more work can be done

• If there is less resistance or opposition to current flow (Ohms) more work can be done

Three factors effecting electron flow

• Voltage– The amount of potential or electrical

pressure

• Amperage– The rate or speed of electron or current

flow

• Resistance– The amount of opposition to electron or

current flow

RESISTANCE

• Opposition to Current Flow• Restriction• Measured in Ohms• Omega symbol• R

RESISTANCE• Is opposition to current flow – Measured in ohms• The size, type, length, temperature & physical

condition of a conductor will affect its resistance • If resistance increases current flow will decrease• If resistance decreases current flow will increase • Voltage is dropped or consumed as current flows

through resistance

VOLTAGE DROP

• Is the amount of electrical pressure lost or consumed as it pushes current through a resistance

• The Sum (total) of all voltage drops in an electrical circuit will always equal source voltage – all the voltage is used up.

Measuring• Voltage (Electrical pressure)

– Measured with a volt meter that is connected in parallel with the circuit

– Voltage can be measured with the circuit on or off• Amps (Flow of electrons)

– Measured with an Ammeter that is connected in series in the circuit

– The circuit must be on & operating to measure the flow of electrons or current

• Resistance (Opposition to current flow)– Measured with a Ohm meter – The circuit MUST be off – Unless instructed otherwise the component being

measured should be disconnected & isolated from the rest of the circuit before measuring resistance

VOLTS, AMPS & OHMS HAVE A RELATIONSHIP

• ASSUMING VOLTAGE STAYS THE SAME

• IF RESISTANCE GOES UP, AMPERAGE WILL GO DOWN.

• IF RESISTANCE GOES DOWN, AMPERAGE WILL GO UP.

OHMS LAW

E = VoltageI = Current flowR = Resistance

E / I = RE / R = II x R = E

Relationships• The three measurements all work

together• One cannot change without

affecting another

TRY THESE…

E=12V R=12

E=? R=120

E=12V R=24

E=12V R=? I=24A

THE END