Magnetism Science Notes PDF

Magnetism What is a magnet? What is a magnet? Magnet: anything that attracts or repels magnetic materials magnetic materials have metal in them (usually iron, nickel, or cobalt)  Magnets have TWO poles Magnetic Fields A magnetic field is the region around a magnet where it can attract o...

Magnetism What is a magnet? What is a magnet? Magnet: anything that attracts or repels magnetic materials magnetic materials have metal in them (usually iron, nickel, or cobalt)  Magnets have TWO poles Magnetic Fields A magnetic field is the region around a magnet where it can attract or repel a magnetic material through a force Invisible (unless you use iron filings or compass) Direction of field: always North  South Strength of field: strongest at the poles Magnetic force is strongest at poles Magnetic Fields Drawing Magnetic Field Lines 1. Lines must join opposite poles 2. Lines must have arrows that point N  S 3. Lines must NOT touch each other 4. Lines must NOT cross Magnetic Field Interactions Opposite poles ATTRACT Like poles REPEL ELECTROMAGN ETISM What makes something magnetic? 1. Permanent magnets Stays magnetized for a long time Can power own magnetic field Attracts magnetic material Ex., Lodestone (natural) What makes something magnetic? 2. Temporary magnet Magnetic materials can be energized to become magnets themselves! Magnetism weakens once the external energy source is removed Made from soft magnetic material (iron, steel, nickel, cobalt)  An unmagnetized piece of iron or steel can be temporarily magnetized by stroking it in one direction with a magnet. “Magnetized” means turning magnetic material into a magnet Magnetizing (making electromagnets) One way to magnetize a magnetic material is by using electricity (electro-magnetizing) Made by wrapping wire around a magnetic material The wire wrapping is called the coil The magnetic material inside the coil is called the core When current passes through the coil, the magnetic material becomes magnetized When current is switched off, the magnetic  Electromagnets Need two things… 1. Coil of wire 2. Battery or low-voltage power supply Advantage of electromagnets… Turns on and off Coil is magnetized only when current is flowing Question… How would you determine the orientation of its magnetic field? Electromagnets in action 1. Sorting scrap metal 2. Toasters! 3. Electric bells 4. Electric motors 5. MRI machines  Investigating Electromagneti 3 C’s to Improve Electromagnets 1. Using iron Core - doesn’t work with wood/non magnetic object) 2. Adding Coils - more coils, stronger magnet 3. Increasing Current - add batteries in series - current units = amps (A) - measure current using ammeter Earth as a Magnet Magnetic Earth Over 2,000 years ago, the Chinese discovered that small needles of lodestone would always point the same direction if floated in water Led to the development of the first compasses Allowed explorers to venture the seas and not get lost! Magnetic Earth Magnetic South Pole So, the earth is a giant magnet! The magnetic south pole is NOT exactly at the geographic North Pole (where 🎅 lives) Magnetic poles shift over time Compasses align to earth’s magnetic field lines Magnetic North Pole Magnetic Earth Animals can detect the earth’s magnetic field to help navigate during migration Particles from the sun hit the earth’s strong magnetic field near the poles, creating the aurora borealis Magnetic Earth Scientists aren’t sure what exactly causes the earth to be a magnet Likely, the heat in the core causes the iron in mantle to generate a magnetic field