Electric and Magnetic Forces

• Electric and magnetic fields

  Invisible zones of energy that act between objects exerting forces on each other even though the objects are not in contact
• Electric and magnetic forces

  • Can be attractive or repulsive
• Magnetic field


  The area around a magnet or electric current in which a magnetic force acts

  
• Electric field


  The area around a charged particle or object in which a force is exerted on other charged particles or objects
• M-fields and E-fields can occur between objects without touching
• The closer the objects


  The stronger the force
• Electric field


  The physical field that surrounds electrically charged particles
• Charged particles exert attractive forces on each other when their charges are opposite, and repulse each other when their charges are the same
• Magnetic field


  The region around a magnetic material or a moving electric charge within which the force of magnetism acts

  
• Magnetic poles


  • North and South poles
  • North and South attract
  • North/North and South/South repel

  
• The Earth is a large magnet with a north and south pole

  
• Electric power generators use magnetism to create electricity by moving an object through a magnetic field
• The Earth's magnetic field protects the Earth by deflecting solar winds

  
• Magnetic compasses use Earth's magnetic field to navigate

  
• Neutron stars have the strongest magnetic force of any object in the universe
• Conductors


  Materials that allow electric charge to flow freely
• Insulators


  Materials that do not allow electric charge to flow
• Electric charge


  An electron (a negatively charged particle)
• Types of electric charge transfer

  • Conduction
  • Friction
  • Induction
• Conduction


  Heat/energy moves from one object to another through direct touch
• Conductor


  A substance that allows heat or electricity to go through it (e.g. metal)
• Induction


  Does not require objects to be in direct contact
• Friction


  The frictional charging process results in a transfer of electrons between the two objects that are rubbed together
• Rubber has a much greater attraction for electrons than animal fur
• Electrons are negatively charged particles
• When an object loses electrons, it becomes more positive
• When an object gains electrons, it becomes more negative
• Electromagnet


  A strong, temporary magnet made by an electric current
• Magnetism


  The power to attract iron and other metals in electric currents and magnets
• Electric current


  The rate of flow of electrons in a conductor
• Electric currents have a magnetic field
• Electromagnet


  A magnet that consists of a piece of iron or steel surrounded by a coil, which becomes magnetic when an electric current is passed through the coil
• Magnetars are the most magnetic objects in the universe and are so powerful that they can wipe every credit card in existence on Earth if they were at the same distance as the moon
• If you get too close to a magnetar, the magnetic fields are strong enough to upset your very molecular structure and you would just dissolve

  
• Static electricity


  A stationary electric charge, typically produced by friction, which causes sparks or crackling or the attraction of dust or hair
• Static electricity is created when positive and negative charges aren't balanced
• When an object (or person) has extra electrons, it has a negative charge
• When you touch a doorknob (or something else made of metal), which has a positive charge with few electrons, the extra electrons want to jump from you to the knob, causing a tiny shock