
39
5
Electromagnetism
In the previous chapter, we discussed forces in general and the gravitational force
law in particular. In this chapter, we will discuss the electromagnetic force in some
detail. It is an extremely important force to us since, as was mentioned in Chapter 4,
besides gravity, it is the only other force that has any direct effect on us.
5.1 THE ELECTRIC FORCE LAW
The electric force law is similar, in many ways, to Newton’s law of gravity. It is given
by the equation
F = Kq
1
q
2
/d
2
(5.1)
where q
1
and q
2
are electric charges that are measured in units of coulombs. There
are two different types of charges, positive and negative. The ...