Physics Test Topic 0-7

• Opposites charges


  Attract each other
• Like charges


  Repel each other
• Neutral objects


  Are attracted to charged objects
• The law of electric charge applies to all individual charges
• Neutral objects


  • Have an equal number of protons (+ charges) & electrons (- charges)
• Attraction between positive and negative charges


  Is strong enough to hold the balloon to the wall
• Electrical Energy


  The energy of charged particles
• What uses electrical energy

  • Human body (electrical nerve impulses/ signals)
  • Technology
  • Many other uses
• Negative Charges


  • The charge of electrons
  • Surround the nucleus
  • Can be rubbed off a material
• Positive Charges


  • The charge of protons
  • Inside the nucleus of atoms
  • Held firmly in place, can't be rubbed off
• Static Charge


  • Electric charge that is collected & held in one place
  • Charged by friction (rubbing)
• Static Electricity


  Imbalance between negative and positive charges in/on objects (stays like this until it can be discharged)
• Uncharged Materials


  • Before 2 materials are rubbed together, there is an equal # of protons and electrons
  • Electrically neutral (=charges cancel each other out)
• Charged Materials


  • After 2 materials are rubbed together, electrons are rubbed off one material -> unequal # of protons and electrons
  • Both materials are electrically charged (either + or -)
• Charging by Friction


  1. Charging a material by rubbing

  2. Solid materials become charged due to the transfer of electrons

  3. Friction between 2 objects can result in one object losing electrons & the other gaining electrons
• Charging by conduction


  • Process of transferring charge between objects by touching directly
  • Electrons move from object with excess electrons to object with less electrons
• Charging by induction


  • Process of re-arranging electrons on a neutral object by bringing a charged object close to the neutral object
  • No electrons are actually transferred -> instead, inducing a charge
  • Repositions and shifts the electrons inside the object
• Conductors


  A material that allows electrons (=electric charge) to travel easily throughout -> HIGH electron mobility
• Insulators


  A material that does NOT allow electrons to move easily -> LOW electrons mobility
• Coulomb


  The unit of electric charge
• Source


  Anything that supplies electrical energy (e.g electrical outlets)
• Electrochemical cell


  Electrochemical in electrolytes that transform chemical energy to electrical energy
• Battery


  A connection of 2 or more electrochemical cells
• A dry cell contains a moist paste as an electrolyte & a wet cell contains a liquid as an electrolyte
• Electrical potential energy


  The electrical energy stored in the cell due to the separation of positive and negative charges
• Potential energy


  Stored energy in an object due to its position
• Kinetic energy


  Energy of motion
• Electric Potential Energy


  Electrons lose their stored electrical energy and a battery must be connected to a device
• Electrical Potential Difference


  Measures the difference in electrical potential energy between 2 points in circuit (+ and - terminal a cell)
• Voltage


  Electrical potential difference
• Electric current


  • The continuous flow of electrons in a complete circuit
  • The amount of charge passing a point in a conductor in 1 second
• Electric Load


  A device that converts electrical energy to another form of energy and when electrons move through a load it loses energy and converts. A load resists the flow of current
• Resistance


  The property of any material that slows down the flow of electrons
• Electrical Circuit


  • A complete pathway that allows electrons to flow
  • Must have a source, load, and conductor
  • Connected in a closed loop to allow current to flow
• Open circuit


  • No closed path along which current can flow
  • No continuity due to a "break" in the path
• Closed circuit


  A closed path for electric current to flow continuously
• Short Circuits


  A circuit resistance that is too low
• Resistance


  • The property of any material that slows down the flow of electrons
  • Unit=Ohm
  • Resistor; an electrical component with a set amount of resistance that slows down current
• Voltage and Current


  When voltage increases, current increases as well
• Resistance and Current


  • Bigger diameter tube = less resistance= more current flow
  • Narrower= more resistance= less current flow