Step-by-step explanation:

Chapter 1

Electric Charge; Coulomb’s Law

1.1 The Important Stuff

1.1.1 Introduction

During the second semester of your introductory year of physics you will study two special

types of forces which occur in nature as a result of the fact that the constituents of matter

have electric charge; these forces are the electric force and the magnetic force. In fact,

the study of electromagnetism adds something completely new to the ideas of the mechanics

from first semester physics, namely the concept of the electric and magnetic fields. These

entities are just as real as the masses and forces from first semester and they take center

stage when we discuss the phenomenon of electromagnetic radiation, a topic which includes

the behavior of visible light.

The entire picture of matter and fields which we will have at the end of this study is

known as classical physics, but this picture, while complete enough for many fields of

engineering, is not a complete statement of the laws of nature (as we now know them).

New phenomena which were discovered in the early 20th century demanded revisions in

our thinking about the relation of space and time (relativity) and about phenomena on

the atomic scale (quantum physics). Relativity and quantum theory are often known

collectively as modern physics.

1.1.2 Electric Charge

The phenomenon we recognize as “static electricity” has been known since ancient times.

It was later found that there is a physical quantity known as electric charge that can be

transferred from one object to another. Charged objects can exert forces on other charged

objects and also on uncharged objects. Finally, electric charge comes in two types, which we

choose to call positive charge and negative charge.

Substances can be classified in terms of the ease with which charge can move about on

their surfaces. Conductors are materials in which charges can move about freely; insula-

tors are materials in which electric charge is not easily transported.