5.35 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  relationship in a radial field
  • The gravitational potential and electric potential both have a  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