physics

• Electricity


  Invisible force that provides light, heat, sound, motion
• Elements


  The simplest form of matter
• Atoms


  Smallest piece of an element containing all of the properties of that element
• Components of an Atom

  • Nucleus
  • Protons
  • Neutrons
• Atomic Number


  The number of protons in the nucleus of an atom, identifying the element
• How many protons are in this nucleus?
• Electrons


  • Negatively charged particles
  • Electron Orbitals - Orbits in which electrons move around the nucleus
  • Valence Electrons - The outermost ring of electrons in an atom
• Electron Orbit Numbers and Maximum Electrons

  • 1 - 2
  • 2 - 8
  • 3 - 18
  • 4 - 32
  • 5 - 50
  • 6 - 72
• Atoms like to have their valence ring either filled (8) or empty(0) of electrons
• Copper


  Conductor
• How many electrons are in the valence orbit of copper?
• Sulfur


  Insulator
• Why is sulfur an insulator?
• Conductors


  Electrons flow easily between atoms, 1-3 valence electrons in outer orbit
• Insulators


  Electron flow is difficult between atoms, 5-8 valence electrons in outer orbit
• Electrical Circuit


  A system of conductors and components forming a complete path for current to travel
• Properties of an electrical circuit

  • Voltage (Volts, V)
  • Current (Amps, A)
  • Resistance (Ohms, Ω)
• Current


  The flow of electric charge
• When the switch is off, is there any flow (current)?
• When the switch is on, is there any flow (current)?
• Conventional Current


  Assumes current flows out of the positive side of the battery, through the circuit, and back to the negative side
• Electron Flow


  What actually happens - electrons flow out of the negative side of the battery, through the circuit, and back to the positive side
• The direction that the current flows does not affect what the current is doing; thus, it doesn't make any difference which convention is used as long as you are consistent
• Since this is an engineering course, we will use Conventional Current
• Voltage


  The force (pressure) that causes current to flow
• When the switch is off, is there any pressure (voltage)?
• When the switch is on, is there any pressure (voltage)?
• Resistance


  The opposition of current flow
• What happens to the flow (current) if a rock gets lodged in the pipe?
• Multimeter


  An instrument used to measure the properties of an electrical circuit, including voltage, current, and resistance
• Ohm's Law


  The mathematical relationship between current, voltage, and resistance
• Matter


  Made up of atoms
• Ohm's Law Quantities


  • Voltage (V, Volts)
  • Current (I, Amperes)
  • Resistance (R, Ohms)
• Atoms contain


  • Protons (+)
  • Neutrons (0)
  • Electrons (-)
• If you know 2 of the 3 quantities, you can solve for the third
• Atomic structure


  Structure of atom comprising a nucleus (center) in which the protons (positively charged) and neutrons (neutral) are present. The negatively charged particles called electrons revolve around the center of the nucleus.
• Ohm's Law Formulas


  • V=IR
  • I=V/R
  • R=V/I
• Electrically neutral


  Normally, materials are electrically neutral, however when they come in intimate contact and are separated one gets a positive charge while the other gets a negative charge. The intensity of the charge depends on the nature of the 2 materials, the rapidity of separation and the insulating property of the air at the time of separation.
• Circuit Configurations


  • Series Circuits - Components connected end-to-end, single path for current
  • Parallel Circuits - Both ends of components connected, multiple paths for current
• Electric charge


  Similar to the quantity we call mass of a particle determines how it reacts when a force acts on it. The mass of a particle is a measure of the amount of matter it carries, whereas the charge of a particle is a measure of the amount of "electric-ness" it carries. An electric charge is the amount of charge that is "on" or "carried by" a particle determines how the particle reacts to electric fields.