Electric fields Flashcards
What is an electric field?
region of space in which any object with charge will experience a force
Where do electric fields exist?
around all objects with charge
State Coulomb’s law in symbols.
F = (Q1Q2)/4pi(permeability or free space)r^2
Give the electric field strength at any point in a field.
E = F/Q
Give the unit of electric field strength.
NC^-1
Give the field strength for a radial electric field at a distance r from a point charge Q.
E = Q/4pi(permeability of free space)r^2
How can a uniform electric field be produced?
applying a potential difference between two parallel metal plates
Give the properties of a uniform electric field.
field strength and direction are the same at every point
Give the formula for the magnitude of the electric field strength at any point in a uniform field.
E = V/d
What kind of trajectory will a charged particle entering a uniform field in a direction initially perpendicular to the field have?
parabolic trajectory
Define the absolute electric potential at a point in an electric field.
work done per unit charge to bring a small positive test charge from infinity to that point
Give the formula for the magnitude of the absolute electric potential at a point in a radial field caused by a charge.
V = Q/4pi(permeability of free space)r
What is electric potential difference?
difference between the electric potential at two points in an electric field
Give the formula for the work done in moving a charge between two points in an electric field.
(delta)W = Q(delta)V
What is an equipotential surface in an electric field?
surface where the electric potential is the same at all points
How are equipotential surfaces arranged relative to field lines?
perpendicular to field lines
What shape are the equipotential surfaces in a radial field, and a uniform field?
spheres; flat planes
How is electric field strength related to potential difference?
E = (delta)V / (delta)r
How can the electric field strength at any point in an electric field be found from the graph of V against r?
gradient of the graph at that point
How can the potential difference between two points in a field be found from the graph of E against r?
area under the graph between those two points
