0.20 kg ballWarm Up 10 The ball (0.20 kg) in the diagram is moving at a speed of 12 m/s. What is the momentum of the ball in kg · m/s? Record and bubble in your answer to the tenths place on the answer document.

Magnets are essential parts of today’s world –Electricity would be rare –No hard drives –No MRI (Magnetic Resonance Imaging) machines

Lodestones are naturally magnetic rocks Magnetism was considered the 5 th fundamental force of nature –Gravity –Electricity –Magnetism –Strong Nuclear –Weak Nuclear

Hans Christian Oersted (1820) discovered that Electricity and Magnetism were the same force –You can create a magnet with electricity –You can create electricity with a magnet

Magnets are made of special alloys of metals Magnets always have a North and South Pole –Break a magnet and you still get both poles

Similar to charges and masses, magnets produce a force field, a magnetic field.

A magnetic field is created when a charge moves What is moving to create the magnetic field of a magnet?

Electrons orbit the nucleus AND spin on an axis Their motion creates a magnetic field

Which do you think is more important to magnetism, electrons orbiting the nucleus or the electrons spinning on an axis? Why? Electron spin because the electron orbit is very random

Since all atoms have electrons that move, why isn’t everything magnetic? Destructive Interference cancels out most of the magnetic forces

Magnetic fields of individuals atoms can polarize nearby atoms These create Magnetic Domains inside an object The better aligned, the more powerful the magnet

Magnets can induce temporary magnets Permanent magnets: –Rub a magnet over a piece of iron –Place a piece of iron in a strong magnetic field –Place a piece of iron near a strong electromagnet

What do all three ways have in common? (Think back to magnetic domains) They all try to align the magnetic domains of a piece of iron

Exit Ticket 1 Which way would a compass point if you were 100 m in the air, above the North Pole?