Physics

• Atoms have protons, neutrons and electrons
• Electrons are negatively charged particles that can sometimes when the situation is just right, escape from one atom and move to another
• Movement of electrons is the basis of electricity
• William Gilbert


  Wrote 'De Magnete', in which he made a careful study of electricity and magnetism, distinguishing the lodestone effect from static electricity produced by rubbing amber
• Electricus


  New Latin word meaning "of amber" or "like amber"
• Elektron


  Greek word for "amber"
• The words "electric" and "electricity" made their first appearance in print

  1646
• Hugh Williamson


  Reported a series of experiments to the Royal Society on the shocks delivered by the electric eel
• John Hunter


  Described the structure of the electric eel's electric organs
• Luigi Galvani published his discovery of bioelectromagnetics, demonstrating that electricity was the medium by which neurons passed signals to the muscles


  1791
• Alessandro Volta


  Invented the battery of 1800, made from alternating layers of zinc and copper, providing scientists with a more reliable source of electrical energy than the electrostatic machines previously used
• Hans Christian Ørsted and André-Marie Ampère


  Recognised the unity of electric and magnetic phenomena in 1819–1820
• Michael Faraday


  Invented the electric motor in 1821
• Georg Ohm


  Mathematically analysed the electrical circuit in 1827
• James Clerk Maxwell


  Definitively linked electricity, magnetism and light in his "On Physical Lines of Force" in 1861 and 1862
• As electrons collect on an object, it becomes negatively charged. As electrons leave an object it attains a positive charge
• Charges interact with each other
• When removing clothes from the clothes dryer

  • The clothes seem to stick together
  • Some of the clothes have gained electrons by rubbing against other clothes
  • The clothes losing electrons become positive
  • The negative clothes are attracted to the positive clothes
• Van de Graaf generator (large silver ball)


  • Deposits electrons on the ball
  • When a person places their hand on the ball and the machine is turned on, electrons are transferred to and collected on the person touching the silver ball
• Static electricity


  An electric shock that is caused by the buildup of electrons
• Small amounts of static can cause a slight shock like when you rub your feet along the carpet and touch someone
• Large amounts of static can occur as in the case when clouds discharge static electricity in the form of lightning
• Static electricity


  Stationary or collects on the surface of an object
• Current electricity


  Flowing very rapidly through a conductor
• Current electricity has electrical pressure or voltage, and electric charges flow from an area of high voltage to an area of low voltage

  
• Electric current


  The movement of electrons from one place to another
• Amperes


  The unit of measurement for electric current
• Closed circuit


  Electrons can only follow a complete, unbroken path
• Open circuit


  An incomplete path where electrons cannot flow

  
• Switch


  Allows an open circuit to be closed so electrons can flow in an unbroken path
• Conductor


  Any material that electricity passes through easily (metals are great conductors)
• Insulator


  Any material that electricity does NOT pass through easily (rubber, plastic)
• Electric wires normally have a center made of conducting material but are coated with insulating material
• Resistance


  The measure of how easy or hard it is for electric current to move through a material, measured in Ohms

  
• Insulators have high resistance, conductors have low resistance
• Resistance of wire


  • Depends on the material, length, and thickness of the wire
• Resistance is good sometimes as it causes electrical energy to turn into heat and light energy, without resistance many appliances in our home wouldn't work
• Electromotive force


  The "push" that keeps the current flowing, measured in volts
• When voltage is high, electrons have more energy to do work
• Batteries


  Composed of a chemical substance which can generate voltage which can be used in a circuit