AQA A Level Physics

Revision Notes

7.4.7 Comparing Gravitational & Electrostatic Forces

Gravitational v Electrostatic Forces

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

G Fields v E Fields Table 1, downloadable AS & A Level Physics revision notesG Fields v E Fields Table 2, downloadable AS & A Level Physics revision notesG Fields v E Fields Table 3, downloadable AS & A Level Physics revision notes

  • The key similarities are:
    • The magnitude of the gravitational and electrostatic force between two point masses or charges are inverse square law relationships
    • The field lines around a point mass and negative point charge are identical
    • The field lines in a uniform gravitational and electric field are identical
    • The gravitational field strength and electric field strength both have a 1 / r relationship in a radial field
    • The gravitational potential and electric potential both have a 1 / r relationship
    • Equipotential surfaces for both gravitational and electric fields are spherical around a point mass or charge and equally spaced parallel lines in uniform fields
    • The work done in each field is either the product of the mass and change in potential or charge and change in potential
  • 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 Tip

This topic could come up as long structured answer question, practice summing up this information as you would for a 6 mark question.

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