Why do electric fields exist?
Due to charged particles
How are uniformly charged spheres modelled?
As a point charge at its centre
How do electric field lines represent electric fields? (3)
The arrow shows the direction that a point positive charge moves
At right angles to the surface of a conductor
Separation represents electric field strength
How is a uniform electric field represented?
Equally spaced, parallel lines
Define electric field strength
The force experienced per unit positive charge at a point in an electric field
State Coulomb’s law
The force between two point charges is directly proportional to the products of the charges and inversely proportional to the square of their separation
What are the similarities between gravitational fields and electric fields? (2)
Point masses/charges produce a radial field
Field strength is force per unit mass/positive charge
What is the difference between gravitational fields and electric fields?
Masses always produce an attractive field whereas charges produce both attractive and repulsive fields
What does the capacitance of a parallel plate capacitor depend on? (3)
Separation between the plates
Area of overlap between the plates
The dielectric used between the plates
How does a charged particle move in an electric field? (3)
A charged particle moves away from the plate of the same charge
It experiences a constant electrostatic force, giving it constant acceleration
A particle moving at right angles to the field behaves similarly to a projectile, with constant vertical acceleration and constant horizontal velocity
Define electric potential
The work done in bringing a unit positive charge from infinity to that point in an electric field
When is electric potential zero?
Define electric potential difference
The work done per unit charge between two points around a particle of charge
What is an equipotential?
A line or surface along which the electric potential is the same
What does the area under a force-distance graph represent?