0.20 kg ball Warm 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 5th 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?