Electrical Unit Notes

Electricity

Movement of free electrons from one atom to another.

Matter

Anything that takes up space and has mass. Can be liquid, gas, solid, or plasma.

Atoms

Small particles that make up elements. Basic unit of all matter.

Atom make-up:

• Proton: positive charge

• Neutron: no charge (neutral)

• Electron: negative charge

Law of charges:

• Like charges repel each other

• Unlike charges attract each other

Electron Theory:

• (negative to positive)

• Electrons will flow from where there are many (- terminal) electrons to where there are few (- terminal) electrons.

• This theory is the one that is generally accepted by the electronic industry. (real theory) → Reality

Conventional Theory:

• States that electrons flow form positive to negative.

• This theory is the oldest and serves as the basis for all wiring diagrams.

• used for diagnosing cars.

Car batteries are what?

• DC - Direct current (electrons only flows one way)

Conductors:

• Conductors (roads) have 1-3 electrons in outer orbit of an atom. They are easily knocked out of orbit.

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

• (1-3 electrons in atomic structure, more conductible)

• Transition metals in the periodic table of elements.

Insulators:

• Insulators have 4 or more electrons in outer of the atom. Hard to knock the electrons out of orbit because they have a strong magnetic pull to the protons in the nucleus of the atom.

• Glass, ceramics, plastics, rubber, fiber, porcelain, paper, and wood are common insulators.

• (Asian cars use soy → Animals love to eat it.)

• (Honda → Bitter tasting agent → animals stop eating wires due to bitter taste.)

Ways you create electricity:

• Electrochemical (battery) *

• Electromagnetic (alternator) (all power sources) *

• Electrostatic

• Photovoltaic (solar energy) (30% efficient) *

• Piezoelectric (pressure on crystal)

Volatge:

• (electromotive force, EMP)

• Pressure or amount of push behind the electron flow. This pressure is known as voltage.

• Volage is measured in volts with a voltmeter. (multimeter does all)

• Label = v

• Kv = kilovolts or 1000 volts ( thousands of volts)

• mV = millivolts or .001v (smaller than 1)

• School Zone (speed) → low voltage

• NASCAR Race (speed) → High voltage

• conductors = roads

Amperage:

• Quantity of how many free electrons flow through a conductor.

• Current flow is measured in amperes (amps).

• Label = A

• Measured with an ammeter.

• milliamps = 0.100 amps (less than 1)

• Amps = current (same term)

• Late Saturday night (amount of people driving at that time) → low amps

• 4:00pm Friday rush hour traffic (amount of people driving at that time) → High Amps

• Amount of electrons/cars on the road/conductors.

• *AMPS CAUSES HEAT*

Resistance:

• The opposition to current flow. Caused by electrons bumping into each other. A poor conductor has greater resistance than a good conductor.

• Measured in Ohms with an ohm meter.

• symbol is omega (horse shoe) Ω

4 things that effect the resistance:

• Type of material

• length of the wire - longer wire has more resistance.

• Width of the wire - this wire has more resistance. ( bottle neck, the bigger the better)

• Temperature - heat increases resistance.

Always there you can never get rid of resistance completely just minimize it.

Construction on a road closing 2 out of 3 lanes, all cars/electrons need to travel on that one tiny lane on the road/conductor.

electromagnet:

• a magnet that is created by using electricity.

• Wrap a wire around an iron core and run electricity through the wire will generate a magnet

3 ways to increase strength of magnetic field:

• use more loops of wire

• use thicker (larger) wire

• Run more electricity through the wire

Magnetic induction:

• use magnetism to create electricity

• pass a wire through a magnetic filed will cause electrons to flow in the wire.

• 4 ways to increase the output or amount of electricity:

• run more loops of wire through the filed.

• run longer wire through field ( thicker)

• Run wire through filed faster

• create a stronger magnetic filed

Circuits

• something which has a beginning point, an ending point, and a specific path to follow. It repeats over and over again.

5 basic components an electrical circuit must have!

• power source (battery)

• conductor (wires for electrons to flow through)

• Load (something to operate, like a light bulb or motor)

• Switch (control device)

• Fuse (circuit protection)

Circuit breakers ( house example/ comparison)

Series circuit:

• Characteristics: (not lights)

• Only one path for current to flow.

• Each load is dependent on the other in order to work.

• One goes out, they all go out.

Series parallel circuit:

• It is a mix of both

Parallel circuit:

• Characters:

• multiple paths for the electrons.

• Each load is separate from each other.

Ground:

• Ground means to complete the circuit back to source of power. (Chassis Ground = alternative name)

• Ground symbol (picture)

• Ground goes from positive to the top of the loads. Everything past that is (no charge/volts) (not really but we are not being literal.)

Ohm’s Law:

I = Amperes (current)

R = Ohms (resistance)

E = Volts (electromotive force)

Ohm’s Laws formulas:

• I = E/R

• E = I x R

• R = E/I

Series Circuit Rules!

• In a series circuit, amperage will always remain the same, but the voltage will change.

• 2 ways to find total voltage = Et

• Et (total v) = I • Rt or the sum of all voltage drops Er1 + Er2

• 2 ways to find total resistance = Rt

• Rt = Et/I

• The sum of all R1 + R2 = Rt

Voltage Drop

• The voltage that is lost at it travels through a load or through any resistance.

• Symbol - Er1

• Formula is Er1 = I • R1