Electric and Magnetic FIelds

• Capacitance

  The ratio of the charge stored in a capacitor to the potential difference between the two sides of the capacitor.
• Coulomb’s Law

  The size of the force that acts between two point charges is proportional to the product of their charges and inversely proportional to the square of their separation. It is attractive for opposite charges and repulsive for like charges.
• Dielectric

  An insulating material placed between capacitor plates that prevents charge from crossing between the plates. The dielectric becomes polarised when the capacitor is charged and changes the capacitance of the capacitor.
• Electric Field

   A region of space in which charged particles experience either an attractive or repulsive force depending on the charge of the particle and direction of the field.
• Electric Field Lines

   A way of representing an electric field in a diagram, they point in the direction that a positive charge would experience a force, point positive to negative.
• Electric Field Strength

   Defined at a point. The electrostatic force experienced by a unit positive charge at a that point in the field.

   
• Electric Potential

   Defined at a point. The work done moving a unit positive charge from an infinite distance away to that point.
• Electric Potential Difference

  The work done moving a unit positive charge between two points.
• Electrostatic Force

  The force generated between charges due to Coulomb's Law.
• Equipotential

  Planes of points where the electric potential is the same, no work is done moving charge along these lines.
• Fleming’s Left hand Rule

   The relative direction of motion, field direction and current direction in the motor effect can be represented by the thumb, first finger and second finger of the left hand respectively. For the motion of a charged particle in a magnetic field, its direction replaces the current direction.
• Frequency

  The number of complete oscillations of the current (or voltage) in an A.C circuit per second.
• Magnetic Field

  A region of space in which magnetic materials and moving electric charges feel a force.
•  Magnetic Flux

  The magnetic field passing through a given area. Given by the product of the magnetic flux density and the area.
• Magnetic Flux Density

  The strength of a magnetic field measured in Tesla.
• Magnetic Flux Linkage

  The magnetic flux of a coil found by the product of the magnetic flux and number of turns of a coil.
• Motor Effect

   The force felt by a current carrying wire in a magnetic field.
• Oscilloscope

  A device used to monitor periodically time changing quantities such as voltage or current in an A.C circuit.
• Peak Value

  The maximum voltage or current that an A.C circuit achieves.
• Period

  The time taken for the current (or voltage) in an A.C circuit to complete one full cycle.
• Radial Field

   A field with field lines originating from a point like spokes on a wheel.
• Time Constant

  Describes the rate of charge or discharge of a capacitor. It is the time taken for the capacitor to charge from zero to 63% of its full value or to discharge from full to 37% of its full value.
• Uniform Field

   A field with parallel field lines.