6.2 Electric Fields Flashcards
What is an electric field defined as
A region of space in which charged particles are subject to an electrostatic force
How can charged particles be modelled in an electric field
Point charges (their charge exists at a single point in space)
What fields do point charges have
Radial fields
How are electric field lines drawn depending on the point charges
They point outwards from a positive charge or inwards towards a negative charge
What does the direction of field lines represent in electric fields
The direction of the electrostatic force on a positive charge at that point
How does the field strength of an electric field change with radial distance or the distance from the charge
It decreases
How is the decrease of electric field strength due to distance shown
By the decreasing density of the field lines
How can spherically charged spheres be modelled
As point charges
how do electric field lines generally point
from positive to negative
how do electric field lines exit a surface
equally spaced and perpendicular to the surface
how is the strength of an electric field E defined
the force applied per unit charge on an object
how is the strength of an electric field expressed
E=F/Q
what are the units of electric field strength E
NC^-1 or Vm^-1
is the electric field strength a scalar or vector
vector as is has a direction- the direction the positive charge would accelerate at that point and magnitude- size of the force experienced per unit charge
what does coulombs law state about two point charges
any two point charges exert an electrostatic force between them that is proportional to the product of their charges and inversely proportional to the square of the distance between them
what’s the equation for electrostatic force
F=Qq/4πε0r^2
F= electrostatic force
Q and q= the two charges
r= the separation between the charges
ε0= permittivity of free space (8.85 x 10^-12 Fm^-1)
what’s the value of the constant 1/4πε0
8.99x10^9 Nm^2C^-2
what is permittivity
a constant that defines the ability of a material to become polarized and store charge
what is permittivity of free space
the permittivity of a vacuum and as there is no matter in a vacuum to become polarized this is the lowest value possible
whats the equation for the electric field of a point charge
E=Q/4πε0r^2
what are the forces between particles of an electric field
F ∝ Qq and F ∝ 1/r^2
how is a uniform electric field strength produced
between two parallel oppositely charged plates
whats the force experienced by a particle between two parallel oppositely charged plates
a constant force no matter where it resides between the plates
how is the electric potential at a single point defined
the work done per unit charge to bring a positive charge from infinity to that point (V=W/Q)
