Physics Electric Fields Definitions

Mr Costello things

Define electric potential at a point

The energy required per unit charge to move a positive charge from infinity to that point in the field

Units of electrical potential

JC^-1 or V

Formula for electrical potential at a point around a point charge

1/4piε₀ Q/r

Define electric field strength at a point

The force per unit positive charge experienced by a test charge at that location

Formula for electric field strength at a point around a point charge

1/4piε₀ Q/r²

Units of electric field strength

NC^-1 or Vm^-1

Relationship between electric potential and electric field strength

The electric field strength is the negative gradient of the electric potential; the electric field strength is equal to the negative of the rate of change of potential with distance

Equation for the force acting on a charge in an electric field ‘E’

F = QE

Equation to find electric potential energy of a charge in an electric field

E = QV

State Coulomb’s Law in words

Coulomb's law states that the force between two stationary point charges is directly proportional to the product of their charges and inversely proportional to the square of the distance between them.

Why is electric potential positive for a positive charge

It requires positive work to bring a positive test charge from infinity to a point near it; positive charges are repulsive

How is a uniform electric field created

Two parallel plates with a difference in electric potential

How to calculate a uniform field strength

Divide the potential difference (V) by the distance (d) between the plates; E = V/d