Electrical Fundamentals

Basic Electricity

What is Electricity? Electricity is basically a movement of electrons which can be controlled and used to do work.

Matter includes anything that has mass and occupies space. can exist in three states: solid, liquid or gas.

The Atom smallest size that matter can be reduced to still maintains the properties of the original material groups of atoms are called molecules

HH O A water molecule is made up of two atoms of hydrogen and one atom of oxygen. Not all materials are made up of molecules. Copper is made up of only one type of atom. These materials are called elements.

Atomic Construction The atom is similar to a miniature solar system. The nucleus (in red) is the center of the atom. Inside the nucleus are protons and neutrons. Circling the nucleus are the electrons.

Neutrons ELECTRON NUCLEUS ORBIT PROTON NEUTRON a neutrally charged particle adds atomic weight to the atom

a positively charged particle found in the nucleus number of protons helps determine the charge of the atom ELECTRON NUCLEUS ORBIT PROTON NEUTRON Protons

Electrons ELECTRON NUCLEUS ORBIT PROTON NEUTRON orbit around the nucleus attracted to the positive charge of the protons this attraction keeps them in their orbits

Charges Like charges repel and unlike charges attract. This theory is used to determine the composition of the atom and the strength of the attraction of the particles. Atoms always try to remain electrically balanced.

Balanced Atoms A balanced atom has an equal number of protons and electrons. These atoms are electrically neutral. The negative charge of the electrons cancels the positive charge of the protons.

Ions When an atom has more protons than electrons, we call the atom a positive ion. When an atom has more electrons than protons, we call the atom a negative ion. 2 PROTONS 1 ELECTRON 2 PROTONS 3 ELECTRONS

Electron Orbits Electrons rotate around the nucleus in different orbits called rings, orbits or shells. Bound electrons orbit the nucleus on the inner rings. They have a strong magnetic attraction to the nucleus. Free electrons are found in the outermost ring called the Valence ring. FREE ELECTRON BOUND ELECTRONS VALENCE RING

Free Electrons NUCLEUS Only the free electrons in the outermost shells are free to move from one atom to another. This movement is called electron flow. Because these electrons have a weak attraction to the nucleus, they can jump from atom to atom very easily. FREE ELECTRON

Insulators 5-8 ELECTRONS IN THE OUTER SHELL An insulator is a material which inhibits the flow of electrons. The valence ring has 5 or more electrons in it. With so many electrons in the outer shell, the force of attraction to the nucleus is strong and the electrons cannot be easily moved from atom to atom. Some insulating materials include glass, plastics, and rubber.

Conductors 1-3 FREE ELECTRONS IN THE OUTER RING The conductor allows the transfer of free electrons very easily. There are only 1-3 free electrons in the valence ring and their attraction to the nucleus is very weak. Some good conductors are copper, gold and aluminum.

Semiconductors 4 ELECTRONS IN THE OUTER SHELL Semiconductors have 4 free electrons in their valence shell. They are neither conductors nor insulators. They are typically used in the manufacture of solid state components such as transistors, diodes and integrated circuits. Some examples of semiconductors are Silicon, Germanium and Carbon.

Current Flow The Conventional Theory or Hole Theory, states that current flows from positive to negative. As electrons move toward the positive terminal, the holes they leave behind move toward the negative terminal.

Current Flow The Electron Theory states that electrons jump from atom to atom toward the positive terminal of the battery.

Voltage Voltage can best be described as the force which “pushes” electrons through a conductor. It can also be called Electromotive Force or EMF. The greater the difference of electrons between two materials, the higher the “potential difference” becomes.

Measuring Voltage always measured with a voltmeter always measured in parallel measures the potential difference between two points in a circuit unit of measure is the volt named after the scientist Alessandro Volta VOLTMETER

Voltage Units

Current Current describes the quantity of electrons which flow past a certain point in a circuit in one second. Higher voltage will produce higher current flow if the resistance remains the same in a circuit.

Measuring Current measured using an ammeter always placed in series with the circuit unit of measure is the Ampere or Amp named after Andre-Marie Ampere, a French scientist

Amperage Units

Effects of Current Flow HEAT: When current flows through a conductor, heat is generated. The higher the current flow, the greater the heat. ELECTROMAGNETISM: When current flows, a small magnetic field is created around the conductor. The higher the current, the stronger the magnetic field becomes.

Resistance Resistance is the force which opposes the flow of electrons. High resistance will allow fewer electrons to flow while low resistance allows many electrons to flow. High resistance can also create heat.

Measuring Resistance no current flow should be present when measuring resistance unit of measure is the Ohm, named after Georg Simon Ohm, a mathematician created Ohm’s Law for calculating voltage, current and resistance in a circuit

Resistance Units

Factors affecting Resistance LENGTH: the longer the conductor, the higher the resistance. DIAMETER: the narrower the conductor, the higher the resistance. TEMPERATURE: depending on the material, most will increase in resistance as temperature increases. PHYSICAL CONDITION: any damage will increase resistance. TYPE OF MATERIAL: the type of material will determine the resistance

What does Corrosion do to a Circuit?

Figure 3 - Electrons moving in a wire.

Figure 7 - Insulation on conductor.

Figure 8 - Insulation preventing conductor contact.

Figure 9 - Plastic insulation on wiring.

Figure 10 - Starter solenoid and alternator stator.

Figure 11 - Rear window defogger.

Figure 12 - Insulation damaged and conductors shorted together.

Figure 13 - Protection of insulators and conductors.

Figure 14 - Lightning shows the effects of voltage.

Figure 15 - Typical battery.

Figure 16 - Electromagnetic induction. (Courtesy Toyota Canada Inc.)

Figure 19 - Resistance decreases as cross-sectional area increases.

Figure 20 - As length increases, resistance increases.

Table 2

Figure 22 - Electron flow from a battery through a bulb.

Table 3

Figure 24 - Carbon tracking of ignition coil.