Magnetism and Earth's Magnetic Field

Mr. Beck introduces magnetism and electromagnetism, discussing the history of magnets, the concept of magnetic poles, and Earth's magnetism. He explains the fundamentals of magnetism at the particle level, including the role of electrons and magnetic domains. The lecture covers how permanent magnets are formed and the evidence magnetism provides for plate tectonics. Finally, magnetic field lines and their properties are described, setting the stage for further exploration in subsequent lectures.

What was the original use of lodestone in ancient times?

• As a weapon

• As a tool for navigation

• As a currency

• As a decorative stone

Why does the North Pole of a compass point towards the Earth's geographic North?

• Because the compass is defective

• Because the Earth's geographic North is a North Magnetic Pole

• Because of gravitational forces

• Because the Earth's geographic North is a South Magnetic Pole

What happens when a magnet is broken into two pieces?

• Each piece becomes electrically charged

• Each piece becomes a smaller magnet with both North and South poles

• Each piece loses its magnetic properties

• Each piece becomes a monopole

What is a magnetic domain?

• A region where all atoms are aligned in different directions

• A region where a significant number of atoms are aligned in the same direction

• A region with no magnetic properties

• A region with only South poles

What is the role of unpaired electrons in magnetism?

• They have no effect on magnetism

• They create electric fields

• They contribute to an atom's magnetic properties

• They cancel out magnetic properties

How can a piece of iron be turned into a permanent magnet?

• By painting it with magnetic paint

• By exposing it to sunlight

• By freezing it in water

• By heating it and letting it cool in a magnetic field

What evidence supports the theory of plate tectonics?

• The presence of fossils on different continents

• The shape of the continents

• The mirrored magnetic patterns on either side of the mid-Atlantic ridge

• The distribution of earthquakes

What causes the Earth's magnetic field to reverse?

• Solar flares

• Changes in the Earth's orbit

• Movements of molten iron in the Earth's outer core

• Tectonic plate movements

What is the nature of magnetic field lines around a magnet?

• They start and end at the same point

• They form complete loops

• They are straight lines

• They only exist outside the magnet

How do magnetic field lines behave inside a magnet?

• They disappear

• They go from North to South

• They go from South to North

• They become straight