The definition of an electric field is
the electric force exerted on a charged
particle per unit charge, just like our
all objects with mass produce a
gravitational field, all particles with
charge produce an electric field. By
convention,  electric field show the
direction that a positive particle will
experience a force. So if I have an
electric field pointing to the right, a
positive particle inside it will
experience a force pointing to the right
while a negative particle will
experience a force to the left. If we
have some sort of weird curvy field, it
would be the same. A positive particle at
this location in the field would
experience a force pushing it upwards,
slightly to the right; A negative
particle at the same position would
experience a force pushing it down and
slightly to the left.
Think about your experiences with
electrostatic charge. That time when you
rub the balloon against your hair and is
stuck to the balloon, the longer you rub
the balloon the more hair sticks. More
force is required to hold up more hair,
so the longer you rub the balloon the
more force it gains from electrostatic
charge. We also know that the longer you
rub the balloon the more charge is
exchanged. So it makes sense that the
force will increase as charge increases.
The next question would then be exactly
how much force does the charged particle
experience inside an electric field? Well,
the force exerted by an electric field
on the charged particle is given by F
equals E times Q, where F is the force in
Newtons,
E is the strength of the electric field
in Newton's per coulombs, and Q is the
charge in coulombs. If we just look at
the units on this equation, then it's
Newton's per coulombs times coulombs The
coulombs cancel and we end up with
Newton's which is the unit for force. So
the unit's make sense. As the charge
increases, the force increases which is
what we expect from real-life experience.
This equation also tells us that the
force increases as the strength of the
electric field increases. So a stronger
field will exert a stronger force on the
charged particle. We can't see electric
fields but we
can see the effects they have on their
surroundings, such as when you're woollen
jumpers stick together in the dryer.
