physics terms

• Electric charge or “charge” is a fundamental property of matter that determines how it reacts to electric and magnetic fields
• • electrics (objects)
• • electricity (ability)
• • Greek word “elektriks” which means amber
• ELECTROSTATICS

  • study of all phenomena associated with electric charges at rest
• Law of Conservation of Electric Charge

  “The total electric charge in an isolated system never changes”
• Evidence for electric charge

  1. Static Electricity
  2. Lightning
• • Lightning

  This discharge occurs between electrically charged regions of a cloud.
• Atom – smallest particle of the element
• Conductors

  • materials through which charge can move freely
• Conductors

  Ex. Metal, Human Body, and Tap Water
• Insulators

  • Conduct charge poorly or do not charge at all
• Insulators

  Ex. Rubber, Plastic, Glass
• Semi-conductors

  • Electrical properties between those of insulators and conductors
• Semi-conductors

  Ex. Silicon and Germanium
• • Doping – process of adding some element to improve conductivity of semiconductors
• Superconductors

  • materials that are perfect conductors, allowing charge to move without any hindrance below some critical temperatures
• Superconductors

  Ex. Mercury, Vanadium, and Tin
• Process of Charging

  • If an atom gains electron, it becomes negatively charged

  • If an atom loses electron, it becomes positively charged
• Charging by Friction

  • Results when two different materials are rubbed together
• • Electron Affinity measure of the attraction of an atom to an electron
• Electron Affinity

  • Tendency of an atom to become negatively charged
• • Triboelectric Series ranking of the materials based on electron affinity
• Triboelectric Series

  • the one that is higher on the list will become the positively charged
  • the one that is lower on the list will become the negatively charged
• Triboelectric Series

  It determines which materials will be most likely having a positive charge and negative charge.
• Charging by Conduction

  • Requires physical contact between a charging body and a neutral body
• Charging by Conduction

  • The sign of the charge acquired by the neutral body is the same with that of the charged body
• Charging by Induction

  • A neutral body may also be charged without physical contact with a charged body 
• Charging by Induction

  • The body to be charged is brought very near the charging body
• • Polarization – slight separation of charge makes one side of the atom somewhat positive and the opposite side somewhat negative
• Forces Between Two Electrical Charges

  The force between two electrical charges is

  • Directly proportional to the magnitude of each charge (q1, q2)

  • Inversely proportional to the square of the separation between their centers

  • Directed along the line connecting their centers
• Superposition Principle states that the total electric force a particular charge experiences due to a number of other charges is the vector sum of all individual forces.