For a charge distribution, with
cfw_qi at cfw_ri:
The net electrostatic force on
r
q0 at r is:
F = k
q i q0
ri
v v2
r ri
r
The net electrostatic field at r
is:
E = F / q0 = k
qi
ri
v v2
r ri
The Principle of Superposition
Problem solving:
There is a unifo
PHYS2114
General Physics II
Electric field
By electric charge
Magnetic field
By moving e. charge
Light
By accelerating charge
ELECTRIC CHARGES
Two types of electric charges:
Protons: positive, +e
Electrons: negative, -e
The unit of an electric charge
Electrostatic Force
The electrostatic force between
two point charges obeys Coulomb's
Law:
r
q1q2
F = k 2 r
r
1
9
2
2
where k =
= 8.99 10 N m / C
4 0
12 2
2
and 0 = 8.85 10 C / N m .
Problem Solving:
If two persons (50 kg each) stood
at arms length (0.5 m