Pigeon Magnetism: Not Flying Blind Answer the following questions in COMPLETE SENTENCES. 1. How did scientists originally think pigeons oriented themselves? 2. What is one hypothesis for how pigeons now orient themselves? 3. How does this article show that the field of science is “changeable”?

Chapter 17 Magnetism

What is Magnetism?

Properties of Magnets A permanent magnet is a material that keeps its magnetic properties. A permanent magnet is a material that keeps its magnetic properties. If a material is magnetic, it has the ability to exert forces on magnets or other magnetic materials nearby. If a material is magnetic, it has the ability to exert forces on magnets or other magnetic materials nearby.

Properties of Magnets All magnets have two opposite magnetic poles, called the north pole and south pole. All magnets have two opposite magnetic poles, called the north pole and south pole. If a magnet is cut in half, each half will have its own north and south poles. If a magnet is cut in half, each half will have its own north and south poles.

Problem Solving Scenario… Dear Scientist, I own a jewelry store and recently I have made a lot of money using magnets to make earrings, necklaces, and even bracelets. Unfortunately, I only have one big magnet left, but I need to make 3 different pieces of magnetic jewelry. Since I only make money if my jewelry is magnetic, I was wondering if breaking the big magnet into smaller pieces will damage the magnet and make it non-magnetic, or if breaking the big magnet will actually make a few smaller magnets. Please respond as soon as possible! Thanks, Julie Magnets Take out a half sheet of paper Write your name on the top

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

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

Magnetic Field Demo Links: Links: 3mrs4 3mrs4 3mrs4 3mrs4 ve8&feature=results_video&playnext=1&list= PL4691F6B67944ECDB ve8&feature=results_video&playnext=1&list= PL4691F6B67944ECDB ve8&feature=results_video&playnext=1&list= PL4691F6B67944ECDB ve8&feature=results_video&playnext=1&list= PL4691F6B67944ECDB DApZQ&feature=results_video&playnext=1&li st=PL4691F6B67944ECDB DApZQ&feature=results_video&playnext=1&li st=PL4691F6B67944ECDB DApZQ&feature=results_video&playnext=1&li st=PL4691F6B67944ECDB DApZQ&feature=results_video&playnext=1&li st=PL4691F6B67944ECDB

Magnetic Field Lines A compass needle is a magnet that is free to spin. A compass needle is a magnet that is free to spin. A compass needle aligns with the local magnetic field A compass needle aligns with the local magnetic field

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

Earth’s Magnetism Earth’s Magnetism Studies of earthquake waves reveal that the Earth’s core is made of hot, dense molten metals. Studies of earthquake waves reveal that the Earth’s core is made of hot, dense molten metals. Huge electric currents flowing in the molten iron produce the Earth’s magnetic field. Huge electric currents flowing in the molten iron produce the Earth’s magnetic field.

Check In! In your notebook, answer the following questions: In your notebook, answer the following questions: 1. Magnets have _____ & _____ poles 1. Magnets have _____ & _____ poles 2. Magnetic force is due to the movement of _______ in an atom 2. Magnetic force is due to the movement of _______ in an atom 3. The force of a magnet gets _______ (stronger or weaker) as you move farther away 3. The force of a magnet gets _______ (stronger or weaker) as you move farther away 4. Earth’s magnetic field comes from ______ ___ in its core 4. Earth’s magnetic field comes from ______ ___ in its core

Geographic & Magnetic Poles Earth’s geographic North Pole is actually a south magnetic pole Earth’s geographic North Pole is actually a south magnetic pole A compass needle’s “north” end is actually attracted to Earth’s “south” magnetic pole!

Declination and “True North” Earth’s geographic north pole and magnetic south pole are not located at the exact same place, so a compass will not point directly to the geographic north pole. magnetic declinationmagnetic declination: the difference between the direction a compass points and the direction of the geographic north pole magnetic declination

Declination and “True North” Magnetic declination is measured in degrees and is indicated on topographical maps. Magnetic declination is measured in degrees and is indicated on topographical maps. Most good compasses contain an adjustable ring with a degree scale used to compensate for declination. Most good compasses contain an adjustable ring with a degree scale used to compensate for declination.

Declination in New Brighton 0° 15' E ± 0° 24' changing by 0° 4' W per year 0° 15' E ± 0° 24' changing by 0° 4' W per year

Earth’s Magnetism Earth’s Magnetism Earth’s magnetic field is losing approximately 7 percent of its strength every 100 years. Earth’s magnetic field is losing approximately 7 percent of its strength every 100 years. If this trend continues, the magnetic poles will reverse sometime in the next 2,000 years. If this trend continues, the magnetic poles will reverse sometime in the next 2,000 years.