D2

• Coulomb's law


  the force between two point charges is inversely proportional to the square of the separation and proportional to the product of the charges
• point charge 


  a charged body of no size
• electric field 


  a region in space in which a charged particle will experience an electrical force
• electric field strength


  the electrical force acting on a unit positive test point charge
• electric field line


  a line showing the direction of electrical force on a positive charge
• Millikan's oil drop experiment

  the experiment that showed that charge comes in multiples of the charge on an electron, that is that charge is quantised
• magnetic field


  a region in space in which a magnetic force can act on a moving charge, a current-carrying conductor or a magnetic pole
• magnetic flux density


  the force exerted per metre on a conductor carrying a current of 1A in a perpendicular magnetic field
• magnetic field line


  a line showing the direction of force on a magnetic north pole
• Fleming's left-hand rule


  a way of showing the geometric relationships between the magnetic force, field and current for a current-carrying conductor in a magnetic field
• amp

  an amp is the constant current flowing in two infinitely long, straight, parallel conductors of negligible cross section in a vacuum such that the force between the conductors is 2×10^(-7) Newtons per metre length of the conductors
• electrical potential


  the work done per unit charge to bring a test point positive charge from infinity to where it is an electrical field
• electrical potential energy


  the work doe to bring a charged body from infinity to where it is in an electrical field
• equipotential 


  a line or surface on which the electrical potential is the same at all points