If a plastic sheet of relative permittivity 2.5 is inserted between two point charges placed in vacuum, then the electrostatic force between them
- A. Increases by a factor of 2.5
- B. Decreases by a factor of 2.5
- C. Increases by a factor of 5
- D. Decreases by a factor of 5
Explanation
Relative permittivity appears in the denominator of Coulomb's law, so inserting a medium of relative permittivity 2.5 reduces the force to 1 over 2.5 of its vacuum value. Water, with a relative permittivity of about 80, weakens ionic attraction eightyfold, which is why ionic compounds dissociate so readily in it. Air is close enough to 1 that the vacuum formula is used for it.
Related questions
The force between two charges placed in a medium of relative permittivity 4, compared with the force in a vacuum, is
If the distance between two charges is halved and magnitude of charges are also doubled, then the force between these charges becomes:
According to Coulomb's law, the force between two point charges is proportional to
If the distance between two point charges is halved, the electrostatic force between them becomes