D.2- Electric Fields

• What does the conservation of charge state?

  NET charge cannot be created or destroyed.
• What does Coulomb's Law describe?

  The force of attraction or repulsion between two charges is proportional to each charge and inversely proportional to the distance between their centres squared
• What is Coulomb's constant (K)?

  K = 8.99 × 10⁹ N m²/C²
• What is permittivity?

  It is the ability of a substance to store electrical energy in an electric field.
• What defines an electric field?

  A region of space where a charge experiences a force.
• How is electric field strength defined?

  It is the force per unit charge acting on a positive point charge.
• What is the electric field strength inside a conducting sphere?

  Electric field strength is zero.
• What characterizes uniform electric fields between parallel plates?

  Lines are parallel, equally spaced and meet the surface at 90 degrees
• What is viscous drag in Millikan's experiment?

  It is the force acting on drops due to friction as they move through a fluid.
• What are characteristics of opposite charges?

  • They have an attractive force
  • Requires work to separate
  • In an energy deficit
  • Negative potential energy
• What is electric potential energy at a point?

  It is the work done to move a charge from infinity to that point in a field.
• How is electric potential defined?

  It is the work done per unit charge in moving a positive test charge from infinity to the point in the field.
• What are equipotential surfaces?

  They are sets of points that all have the same electric potential.
• What is the potential gradient?

  It is the gradient on a electric potential against distance graph, equal to electric field strength
• What happens when a positive charge moves in the direction of a field line?

  It releases energy and moves to a potential surface with a lower value.