Chapter 17Chapter 17

Magnetism Magnetism

What is Magnetism?What is Magnetism?

Properties of MagnetsProperties of Magnets A A permanent magnetpermanent magnet is a material that is a material that keepskeeps its its

magnetic properties.magnetic properties. If a material is If a material is magneticmagnetic, it has the ability to exert , it has the ability to exert

forces on magnets or other magnetic materials forces on magnets or other magnetic materials nearby.nearby.

Properties of MagnetsProperties of Magnets

All magnets have two All magnets have two opposite opposite magnetic polesmagnetic poles, , called the north pole and called the north pole and south pole. south pole.

If a magnet is cut in half, If a magnet is cut in half, each half will have its each half will have its ownown north and south poles.north and south poles.

Problem Solving Scenario…Problem Solving Scenario…Dear Scientist,Dear Scientist,

I own a jewelry store and recently I have made a lot of money I own a jewelry store and recently I have made a lot of money using magnets to make earrings, necklaces, and even using magnets to make earrings, necklaces, and even bracelets. Unfortunately, I only have one big magnet left, but I bracelets. Unfortunately, I only have one big magnet left, but I need to make 3 different pieces of magnetic jewelry. Since I need to make 3 different pieces of magnetic jewelry. Since I only make money if my jewelry is magnetic, I was wondering only make money if my jewelry is magnetic, I was wondering if breaking the big magnet into smaller pieces will damage the if breaking the big magnet into smaller pieces will damage the magnet and make it non-magnetic, or if breaking the big magnet and make it non-magnetic, or if breaking the big magnet will actually make a few smaller magnets.magnet will actually make a few smaller magnets.

Please respond as soon as possible!Please respond as soon as possible!

Thanks, Thanks, Julie MagnetsJulie Magnets

Take out a half sheet of paperTake out a half sheet of paper

Write your name on the topWrite your name on the top

Properties of MagnetsProperties of Magnets

Magnetic forces can pass through many materials with Magnetic forces can pass through many materials with no apparent decrease in strength.no apparent decrease in strength.

Magnetic FieldsMagnetic Fields

The force from a The force from a magnet gets weaker as magnet gets weaker as it gets farther away.it gets farther away.

Magnetic Field DemoMagnetic Field Demo

Magnetic Field LinesMagnetic Field Lines

A A compasscompass needle is a magnet that is free to spin. needle is a magnet that is free to spin. A compass needle aligns with the local magnetic fieldA compass needle aligns with the local magnetic field

Magnetic Field LinesMagnetic Field Lines

The force points away from the The force points away from the north pole and towards the south north pole and towards the south pole.pole.

Earth’s MagnetismEarth’s Magnetism

Studies of earthquake waves reveal that the Earth’s core Studies of earthquake waves reveal that the Earth’s core is made of hot, dense molten metals.is made of hot, dense molten metals.

Huge electric currents flowing in the molten iron produce Huge electric currents flowing in the molten iron produce the Earth’s magnetic field.the Earth’s magnetic field.

https://www.youtube.com/watch?v=Rv7zT953290&authuser=0

Check In!Check In!

In your notebook, answer the following In your notebook, answer the following questions:questions: 1. Magnets have _____ & _____ poles1. Magnets have _____ & _____ poles 2. Magnetic force is due to the movement of 2. Magnetic force is due to the movement of

_______ in an atom_______ in an atom 3. The force of a magnet gets _______ (stronger 3. The force of a magnet gets _______ (stronger

or weaker) as you move farther awayor weaker) as you move farther away 4. Earth’s magnetic field comes from ______ ___ 4. Earth’s magnetic field comes from ______ ___

in its corein its core

Geographic & Magnetic PolesGeographic & Magnetic Poles

Earth’s geographic North Pole is actually a Earth’s geographic North Pole is actually a south south magnetic polemagnetic pole

A compass needle’s “north” end is actually attracted to Earth’s “south” magnetic pole!

Declination and “True North”Declination and “True North”

Earth’s geographic north pole Earth’s geographic north pole and magnetic south pole are and magnetic south pole are not located at the exact same not located at the exact same place, so a compass place, so a compass will not will not pointpoint directly directly to the to the geographic north pole.geographic north pole.

magnetic declinationmagnetic declination: : the difference between the the difference between the direction a compass points and the direction of the direction a compass points and the direction of the geographic north polegeographic north pole

Declination and “True North”Declination and “True North”

Magnetic declination is measured in degrees and is Magnetic declination is measured in degrees and is indicated on topographical maps.indicated on topographical maps.

Most good compasses contain an adjustable ring with a Most good compasses contain an adjustable ring with a degree scale used to compensate for declination.degree scale used to compensate for declination.

Earth’s MagnetismEarth’s Magnetism

Earth’s magnetic field is Earth’s magnetic field is losing approximately 7 losing approximately 7 percent of its strength percent of its strength every 100 years. every 100 years.

If this trend continues, the If this trend continues, the magnetic poles will reverse magnetic poles will reverse sometime in the next 2,000 sometime in the next 2,000 years.years.

https://www.youtube.com/watch?v=XXTEWQdu3aE&authuser=0

Quick RecapQuick Recap

North and South poles attract (come together) North-North or South-South repel (push apart)

Magnetism is due to moving electrons Compasses have a north pole magnet (red)

Attracts to magnetic south (which is north pole)

https://www.youtube.com/watch?v=XXTEWQdu3aE&authuser=0

GroupsGroups Andre Dylan Chris Jazz (lab 1)Andre Dylan Chris Jazz (lab 1) Tas Cole C Anna Tara (lab 3)Tas Cole C Anna Tara (lab 3) Randy Lysandra Mandy Amanda (lab 5)Randy Lysandra Mandy Amanda (lab 5) Herlinda Brianna Jean (lab 7)Herlinda Brianna Jean (lab 7) Eli Mohamed David (lab 9)Eli Mohamed David (lab 9) Cole F Ayrias Devon Maddie (lab 11)Cole F Ayrias Devon Maddie (lab 11) Sam Elizabeth Avery Jackie (lab 13)Sam Elizabeth Avery Jackie (lab 13) Juan Gilberto Zach Kalie (up front)Juan Gilberto Zach Kalie (up front)