1. COULOMB’S LAW The force between two charged objects is
directly proportional to the product of their
charges and inversely proportional to their
separation distance squared.
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2. Felectric kc = q1 q2 d2 In equation form:
F is the force of attraction, measured in newtons,
between charges q1 and q2
k is the Universal Electrostatic Constant, equal to
9.00 x 109 N m2/C2
q1 and q2 are the attracting charges, measured in
coulombs
d is the distance between the charges,
and is measured in meters

3. Charles Augustin Coulomb.
The SI unit of charge
is the coulomb,
named in honor of
Charles Augustin Coulomb.
1 C = charge on 6.25 x 1018 electrons (or protons)
Electric force is a vector and must be treated as such.

4. Coulomb’s unit of measure
Most of the time you will be given μC and will need to convert to Coulomb’s
How to convert…
Number will become 10-6
Example: 6 μC = 6 x 10-6

5. What does the sign tell us?
If both charges have the same sign, they will repel each other.
+ Fel means objects repulse each other
If the charges have opposite signs, the will attract each other.
- Fel means objects attract each other

6. Example Problem # 1
What is the electrostatic force between two objects, +13 μC and –22 μC which are m apart?

7. Example Problem # 2
What is the electrostatic force between two objects of -14 μC and -22 μC that are .86 m apart?