Comparing Electric & Gravitational Fields (Edexcel IAL Physics)

Spec point — 159

Comparing Electric & Gravitational Fields

• The similarities and differences between gravitational and electrostatic forces are listed in the table below:

Table Comparing G and E Fields

Similarities between Gravitational & Electric Fields

• The key similarities are:

  • The magnitude of the gravitational and electrostatic force between two point masses or charges follow inverse square law relationships
  • The field lines around a spherical masses and spherical charges are radial
  • The field lines in a uniform gravitational and electric field are identical (they are parallel and equally spaced)
  • The gravitational field strength and electric field strength both have a $\frac{1}{r^{2}}$ relationship in a radial field
  • The gravitational potential and electric potential both have a $\frac{1}{r}$ relationship

Differences between Gravitational & Electric Fields

• The key differences are:

  • The gravitational force acts on particles with mass whilst the electrostatic force acts on particles with charge
  • The gravitational force is always attractive whilst the electrostatic force can be attractive or repulsive
  • The gravitational potential is always negative whilst the electric potential can be either negative or positive

Exam Hint This topic could require a long structured-answer, so practice summing up this information as you would for a 6 mark question.