Electrical energy

• Charge


  A basic property of matter, measured in coulombs (C)
• Protons


  Positively charged particles in the nucleus
• Electrons


  Negatively charged particles that orbit the nucleus
• Neutrons


  Neutral (uncharged) particles in the nucleus
• Any object that contains an equal number of positive and negative charges will overall be neutral
• Positive and negative charges cancel each other out
• Electric charges interaction


  • Opposite charges attract
  • Like charges repel
• Conductor


  A material that allows electricity to pass through easily
• Insulator


  A material that does not allow electricity to pass through easily
• Metals are extremely good conductors
• Plastics are extremely good insulators
• Electrons can move throughout a material by jumping from one atom to the next
• Electrical wires require electrons to flow freely through the wire
• Insulating plastic is wrapped around conducting metal to prevent electricity from escaping
• Delocalised electrons


  Electrons that aren't bound to any particular atom and can move freely throughout the material
• Electrons inside insulators are held in extremely tight orbits around their respective nuclei
• Pure water is actually a really good insulator
• Normal water is conductive because it contains lots of impurities, specifically ions
• Electron affinity


  The attraction of a material to electrons
• A material with a high electron affinity will have a stronger attraction to electrons than a material with a low electron affinity
• Charging an object


  1. Rubbing materials together

  2. Contact between conductors
• Van de Graaff generator


  A device used to generate charge by transferring charge onto a rotating rubber belt
• Charge spreads evenly across the surface of the metal dome in a Van de Graaff generator
• Charging your body causes your hairs to stand up due to repulsion between charged hairs
• Static electricity is the build-up of electric charge on the surface of an object
• Electric current is the measure of the amount of electric charge that passes by a point each second in a circuit
• Direct current (DC) travels in one direction
• Alternating current (AC) flows back and forth at regular cycles
• Static electricity can discharge when given a path
• Electrons can be transferred by touching, friction, or conduction
• Induction occurs when the movement of electrons is caused by a nearby charged object, without direct contact
• Electrons find it extremely difficult to move through plastics
• When electric charges build up on the surface of an object, it can lead to sparks or flashes of lightning
• An object that has more electrons than protons is negatively charged
• An object that has more protons than electrons is positively charged
• An electroscope can detect static charges
• When an object gains a charge, it is trapped until given a path to escape
• Lightning is an example of electrical discharge by induction
• When a charged object is placed near a neutral object


  It can induce charge in the neutral object
• Bringing an external charge near a neutral conductor will induce a non-uniform distribution of charge in the object