Electric Fields Flashcards
State Coulomb’s Law
The force between 2 point charges is directly proportional to the product of their charges and inversely proportional to their separation squared
If F is negative in the Coulomb’s Law formula how are the particles charged
The charges are opposite, and the force is attractive
In Coulombs Law formula what is Epsilon-Nought? E0
It is the permittivity of free space equal to 8.85x10^-12Fm^-1. The charge per unit area on oppositely charged parallel plates in a vacuum when the electric field strength between the plates is 1 volt per metre. Air can be approximately treated as a vacuum
Define electric field strength
Force per unit charge on a positive test charge
Is electric field strength a scalar or vector and what are its units
- Vector
- NC^-1 or Vm^-1
What is a point charge
A charge that is considered to have all its charge concentrated at a particular point
In a uniform field, how would you work out the electric field strength
E=V/d
V=pd between plates
d=Distance between plates
How can a uniform field be produced and how does the field strength vary between the 2 plates
By connecting two parallel plates to the opposite poles to the opposite poles of a battery. The field strength is the same at all points between the 2 plates
Which way do the field lines point in a uniform field between 2 parallel plates
Towards the smaller number, to the more negative plate
Define Absolute Electric Potential
Work done per unit positive test charge, to move the charge from infinity to that point in an electric field
Is electric potential scalar or vector and what are its units
Scalar
JC^-1 or V
When is the magnitude of electric potential greatest
At the surface of the charge and decreases as the distnace from the charge increases.. It is zero at infinity
What is the gradient of an Electric Potential vs Distance from charge graph (r) equal to
the field strength at that point
What is the area under an Electric Field Strength vs Distance from the charge (r) graph
The change in electric potential
Define electric potential difference
The energy needed to move a unit charge
