Part I
Understanding Physics Fundamentals
In this part . . .
In this part, you make sure you’re up to speed on the skills you need for Physics II. You start with an overview of the topics I cover in this book. You also review Physics I briefly, making sure you have a good foundation in the math, measurements, and main ideas of basic physics.
Chapter 1
Understanding Your World: Physics II, the Sequel
In This Chapter
Looking at electricity and magnetism
Studying sound and light waves
Exploring relativity, radioactivity, and other modern physics
Physics is not really some esoteric study presided over by guardians who make you take exams for no apparent reason other than cruelty, although it may seem like it at times. Physics is the human study of your world. So don’t think of physics as something just in books and the heads of professors, locking everybody else out.
Physics is just the result of a questioning mind facing nature. And that’s something everyone can share. These questions — what is light? Why do magnets attract iron? Is the speed of light the fastest anything can go? — concern everybody equally. So don’t let physics scare you. Step up and claim your ownership of the topic. If you don’t understand something, demand that it be explained to you better — don’t assume the fault is with you. This is the human study of the natural world, and you own a piece of that.
Physics II takes up where Physics I leaves off. This book is meant to cover — and unravel — the topics normally covered in a second-semester intro physics class. You get the goods on topics such as electricity and magnetism, light waves, relativity (the special kind), radioactivity, matter waves, and more. This chapter gives you a sneak preview.
Getting Acquainted with Electricity and Magnetism
Electricity and magnetism are intertwined. Electric charges in motion (not static, nonmoving charges) give rise to magnetism. Even in bar magnets, the tiny charges inside the atoms of the metal cause the magnetism. That’s why you always see these two topics connected in Physics II discussions. In this section, I introduce electricity, magnetism, and AC circuits.
Looking at static charges and electric field
Electricity is a very big part of your world — and not just in lightning and light bulbs. The configuration of the electric charges in every atom is the foundation of chemistry. As I note in Chapter 14, the arrangement of electrons gives rise to the chemical properties of matter, giving you everything from metals that shine to plastics that bend. That electron setup even gives you the very color that materials reflect when you shine light on them.
Electricity studies usually start with electric charges, particularly the force between two charges. The fact that charges can attract or repel each other is central to the workings of electricity and to the structure of the atoms that make up the matter around you. In Chapter 3, you see how to predict the exact force involved and how that force varies with the distance separating the two charges.
Electric charges also fill the space around them with electric field — a fact familiar to you if you’ve ever felt the hairs on your arm stir when you’ve unloaded clothes from a dryer. Physicists measure electric field as the force per unit charge, and I show you how to calculate the electric field from arrangements of charges.
Next up is the idea of electric potential, which you k...
