Electricity and Magnetism

• Like poles repel and unlike poles attract.
• Atoms are made from protons neutrons and electrons.
• Atoms are neutrally charged.
• Friction causes the particles to move when 2 insulating surfaces rub against eachother.
• An electric field is an area around a charge where another charge will experience a force.
• Lightning is caused when particles move causing a build up of charge and then they move causing a current.
• Current - the amount of charge flowing per second.
• Current is measured in amps using an ammeter.
• The cell pushes charges around a circuit.
• Potential Difference is the push that makes a charge move around a circuit.
• Potential Difference is measures in volts using a voltmeter.
• In a parallel circuit the PD is the same for each component as the battery.
• Resistance is how easy or difficult it is to let the current through.
• Resistance is measured in ohms.
• Resistance = Potential difference / current
• Iron , steel , cobalt and nickel are magnetic.
• If a compass is near a magnet they align with the magnetic field lines.
• An electromagnet cannot turn off.
• Electromagnets are stronger than bar magnets.
• The strength of a solenoid depends on the number of turns, length and type of wire used.
• A solenoid is an electrical device that converts electricity into mechanical energy.
• The 8 stores are

  Chemical

  Kinetic

  Thermal

  Elastic

  Gravitational potential

  Nuclear

  Magnets

  Electro - static
• Conservation of Energy - energy cannot be created or destroyed , only transferred from one store to the othe
• Forces determine why something happens
• The chemical store is the amount of energy that can be stored in a chemical bonds so when a chemical reaction takes place that stored energy is released.
• Gravitational potential is the energy stored in an object due to its height from earth - higher is stronger
• Kinetic energy - energy of an object due to its movement
• Nuclear energy - energy stored within the nucleus of atoms
• Thermal energy is the movement of particles
• 4 energy carriers / transfers

  mechanically, electrically, by heating , by radiation
• A battery has a chemical energy store
• Dissipation - when energy is transferred to a store that is not useful
• 3 factors of energy increasing - size , material , temperature
• Heating through particles - conduction and convection
• Conduction - heat is transferred from hotter end to cooler end
• Convection - heat is transferred from the cooler end to hotter end.
• Convection Current

  water at the top cools and becomes cold and sense causing it to sink down and instead the hot rises and turns cold too and repeats until in equilibrium
• Renewable energy sources

  wind waves solar cells biomass hyrdoeectrical geothermal tidal
• If a is hotter than b and they're in contact, the hotter one will transfer energy to the cooler one until they are in equilibrium.
• Metal is a good conductor