Electrostatics

Coulomb's law

• State Coulomb's law:
  The magnitude of the electrostatic force exerted by one point charge (Q₁ ) on another point charge (Q₂ ) is directly proportional to the product of the magnitudes of the charges and inversely proportional to the square of the distance (r) between them:
• Solve problems using the equation:
  
  for charges in one dimension (1D)
  (restrict to three charges).
• Solve problems using the equation:
  
  for charges in two dimensions (2D)
  – for three charges in a right-angled formation
  (limit to charges at the 'vertices of a right- angled triangle').

Electric field

• Describe an electric field as a region of space in which an electric charge experiences a force. The direction of the electric field at a point is the direction that a positive test charge would move if placed at that point.
• Draw electric field patterns for the following configurations:
  • A single point charge
  • Two point charges (one negative, one positive OR both positive OR both negative)
  • A charged sphere
  NOTE:
  Restrict to situations in which the charges are identical in magnitude.
• Define the electric field at a point:
  The electric field at a point is the electrostatic force experienced per unit positive charge placed at that point.
  In symbols:
  
• Solve problems using the equation:
  
• Calculate the electric field at a point due to a number of point charges, using the equation:
  
  to determine the contribution to the field due to each charge.
  Restrict to three charges in a straight line.