Monday, January 18, 2016

Week 1: Debrief (Pt. 2) What is Electricity?

Topics
  • Go over topics and slides on Electricity and make notes on them
Electricity Fundamentals:
  • By understanding how this natural phenomena occurs, Electricity can help you understand how your electronic projects will work
  • There is fundamentally little difference in the stuff we access from a battery or socket with lightning
  • Electricity is the FLOW of an electrical CHARGE; This means electrons are moving
  • AC/DC- alternating current/direct current
  • At the basis of this Atomic structure, the atom is built of three specific building blocks: Neutrons, Protons, and Electrons. Each of these entities has a charge.

  • The Electrons orbit the nucleus (Protons and Neutrons) but normally because of a Electrostatic force. Sometimes though they can shear off one atom and jump to another, this is the basis for the Electrical Flow.

  • The Electrostatic Force acts like phenomena that you know with Magents, where like chages repel and dissimilar charges attract. This is what usually keeps the electrons orbiting the nucleus. This is the glue of our Universe.
  • The outermost electron in the copper atom, aka the VALENCE e-, the furthest away from the protons, thus the force is the weakest and this electron moves from atom to atom fairly easily. When this occurs it is referred to as the current, ELECTRICAL CURRENT!

Video on Carbon Atoms Moving

  • Conductivity- Some materials have these free wheeling valence electrons and some don't. The Materials that have an e- that moves more easily called conductors, material/atoms that don't have the easily movable e- are insulators.

*Please note that these are a spectrum*
Conductors/Insulators

  • Electrons induce friction as they move along
  • All materials have Resistance
  • It can be low to high depending on the atoms in the material
  • NOTE THAT THE INSULATOR/CONDUCTOR DESIGNATION IS A RELATIVE NOTION
  • It should be considered as a spectrum of values better conductors or less conductors as an example
  • High enough electrical current can force through something normally considered an insulator (Opposite is true)
  • IMPORTANT: There are plenty of 'New, Modern' materials designed to do opposite of conventional wisdom
Potential Energy

  • This relates very much to how gravity works even though there are some hefty physics behind this
  • In lamens terms, a current wants to flow from a postivie to a negative; Think of a ball at the top of a hill rolling down hill- Dpeending on how high it is up the hill, the ball has a lot of potential at the top
(More info on this in 'Circuit' section below)
  • The potential energy is the kicker to get an electrical current going
  • The potential is known as the VOLTAGE
  • It acts like a pressure in a system to get the current flowing
  • This will only happen if the positive is connected continuously to the ground, then you have a continuity

  • Positive to Negative (Positive to Ground) is the convention current flow (Ironically the electrons flow the other direction)



What is a Circuit?
  • A continuous current in a roughly circular line, route, or movement that starts or finishes at the same place
  • In terms of electricity, it means that electrical sources are like pumps. Pumps always have two sides, and outlet that blows something out, and an inlet that sucks something up.
  • We build these circuits because we want electricity do useful things. We create these circuits so that we can make the current flow to light up, make noise, runa program, etc. We call these things 'loads', because they 'load down' the power supply like how we are 'loaded down' when carrying stuff.
(How an LED Throwie works)
  • Short Circuit- DO NOT DO THIS!!! If you connect a wire directly from the positive to the negative side of a power supply, you can cause your battery to die or worse; A Chort Circuit can be attached to the ground by mistake and will cause friction, and friciton causes heat so next thing you know, you've burned the entire lab to the ground
  • An OPEN CIRCUIT has a break in the path; The device or action you are trying to perform will not perform/occur unless you CLOSE the path


  • In the next section, we'll cover how this diagram applies to show the relationship between the voltage (V), current (I), and resistance(R)

Ohm's Law
  • Goerg Ohm codified the relation between Voltage, Resistance, and Amperage published in 1827
The Trinity
  • Voltage is the difference in charge between two points
  • Current is the rate at which the charge is flowing
  • Resistance is the material's tendency to resist the flow of charge (Current)
  • Think of a hose pushing out water as a current; The higher the pressure, the higher the flow and vice versa
  • With electricity, we measure charge flowing through the circuit over time
  • Current is measures in AMERES (aka "Amps") the number pf particles passing a point per second
  • Amps are represented in equations by the letter "I"
  • 1 Amp= 6,241,507,648,655,549,400 e- per second

  • Voltage is electrical pressure
  • The more potential that wants to flow to the ground
  • The more water there is in the tank, the higher the charge, and the more pressure there is measured in the outlet

  • There is a relationship that can found between current adn voltage
  • You can output the same amount of Current by increasing the pressure (Voltage) on a system
  • So this action can help anticipate the other way you could effect this

  • Resistance is measured in Ohm's schematics with the Greek letter 'Omega'
  • Resistance can be placed onto a system o control current by using a component called a resistor
  • Resistance is a material's tendency to resist the flow of charge (Current)
  • If we have similar values for voltage but different resistance, the currant value will change



  • This is a common mnemonic to help remember the equation
  • The Triangle suggests Ohm's Law in that: I=V/R, R=V/I, V=I*R
  • Note that when using these formulae, V will be measure d in Volts, I (amerage) in Amperes, and R (resistance) in Ohms

Example:
  • You choose to add an LED that can only handle 30mA (milliamps) of current to your project so you can tell the battery is on. You know the source is a 9v battery. What value resistor should you choose to keep the LED from turning into slag heap?
  1. V= 9 volts, R= 30 miliAmps (.30)
  2. V=I*R
  3. I=V/R= 9/.03
  4. That value will keep the 9 volt battery to a 30 mA current

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