Download An electric field is said to exist in a region of space if an electric

An electric field is said
to exist in a region of
space if an electric
charge placed in that
region is subject to an
electric force.
An electric line of force
is a line so drawn that
a tangent to it at any
point indicates the
orientation of the
electric field at that
point.
Lines of force originate
at the surface of a
positively charged body
and terminate at the
surface of a negatively
charged body.
A line of force shows
the direction in which
a positive test charge
would be accelerated
in that part of the
field.
The electric field
intensity is
proportional to the
number of lines of
force per unit area
normal to the field.
The electric field
intensity, E, at any
point in an electric
field is the force per
unit positive charge
at that point.
E = F/q
E is electric field intensity in
newtons per coulomb, N/C
F is the force in Newtons
q is the test charge in coulombs
The force on a
10 mC charge is
7 Newtons. What is
the magnitude of
the electric field?
An electrostatic charge is
placed in an electric field
that has an intensity of
5
1.50 x 10 N/C.
The charge experiences a
force of 2.10 N. Calculate
the magnitude of the charge
in mC.
Since
E = F/q and
2
F = kq1q2/d ,
then
2
E = F/q = kq1q2/qd .
E = kq1q2
2
/qd
The test charge q
cancels out and
2
E = kq/d .
E=
2
kq/d
This is the formula for the
electric field strength at a
distance “d” produced by
a point charge “q”.
This field strength is a
vector.
What is the electric
field 0.5 m from a
7 mC charge? What
is the direction of the
field?
What is the electric
field 0.4 m from a
-3 mC charge? What
is the direction of the
field?