electric fields Flashcards
coulombs law of force
for 2 point charges, the force between the charges is proportional to the product of their charges and inversely proportional to the square of the distance between them
electric field
a region in space which an electric charge experiences an electric force
electric field strength
at a point in an electric field, is the force per unit charge of a small, positively charged objects at that point in the field.
electric potential (V)
the work done per unit charge on a small positively charged object to move it from infinity to that point
equipotential
a line or surface along which the electric potential is constant
potential energy
the energy an object has due to its position
permittivity of free space
the charge per unit area (in coulombs per square meter) on oppositely charged parallel plates in a vacuum, where the electric field strength between the plates is 1 volt per meter
potential difference
work done per unit charge between 2 points when a positive test charge is moved from 1 point to the other
potential gradient
at a point in a field, is the change of potential per unit charge of distance along that field line at that point. at any given point, potential gradient = - field strength
radial field
a field in which the field lines are straight and converge or diverge from a single point
relative permittivity
the ratio of charge stored by a parallel plate capacitor with dielectric filling the space between the plates to the charge stored without the dielectric (for the same p.d)
what type of law is coulombs law?
inverse square law
what is the equation for work done in moving a charge Q through a potential difference V?
W = QV
what is another term for “charge per unit area”?
surface charge density
if you increase the charge per unit area on a conductor, what happens to the electric field strength?
E = σ / ε0
σ = surface charge density
σ increases so electric field strength increases
when considering multiple charges, how do you combine electric field strength?
electric field strength is a vector quantity, so you have to think about the direction of the field strength due to each charge to combine them
when considering multiple charges, how do you combine electric potential?
electric potential is a scalar quantity, so you can just add them together.
what equations do you need when working out the motion of an electron between 2 charged plates
SUVAT equation
F = ma
F = EQ
Ed = V
what word can be used to describe the motion of an electron between 2 parallel plates?
projectile/parabolic
