Chapter 24

What is the source of the magnetic force?

Electric charges in motion are the source of magnetic forces

The fundamental rule of the attraction and repulsion of magnets is that

Same poles repel each other; Opposite poles attract

What is very important difference between electric charges and magnetic poles?

Electric charges can be isolated, magnetic pole cannot

How do magnetic poles differ from electric charges?

Magnetic poles are always paired and cannot be isolated. Electric charges can exist as singular

How does magnetic field strength relate to the closeness of magnetic field lines are about a bar magnet?

The field strength where the field lines are claser.

What produces a magnetic field?

Electric charges in motion

What two kinds of motion do electrons in an atom appear to have?

Revolution and Spin

Magnetic, Domains are composed of clustered ______

Aligned Ion Atoms

What is the difference between unmagnetized iron nail and a magnetized iron nail at the micro level?

In an unmagnetized nail, iron atoms are unaligned. In a magnetized nail, iron atoms are mainly aligned.

Why is every piece of iron not a magnet ?

Because the domains in ordinary iron are not aligned

If you drop an iron magnet on a concrete sidewalk it will become a weaker magnet. Why?

Vibrations provide energy to randomize the magnetic directions of the domains.

Why is iron magnetic and wood not?

Individual iron atoms are strong enough align the neighbor atoms. The atoms are wood are much weaker

If a compass is moved in a circle around a current-carry wire, the needle will be pointing _____

Always tangent to the circle

What effect does Earth’s magnetic field have on the intensity of cosmic rays striking Earth’s surface?

It reduces the Intensity

True or False. A charged particles must move in a stationary magnetic field in order to experience a force due to the field

True

The magnetic field about Earth takes a shape _____

Similar to that of an interior bar magnet

The cosmic rays deflected most by Earth’s magnetic field are above the ______

Equator

What is the cause of Aurora borealis (the northern light)?

The Earth’s magnetic field guides trapped charges particles to follow field line toward the poles, where they collide with the atmosphere, causing a glow

When do cosmic rays penertate your body?

All the time

What are magnetic pole reversals?

The poles of the Earth’s magnetic field undergo reversals