Magnets And Magnetic Fields. Review Just like Electricity, magnets work in FIELDS. Fields are drawn with VECTORS Review: Up, Down, Left and Right

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Text of Magnets And Magnetic Fields. Review Just like Electricity, magnets work in FIELDS. Fields are drawn...

Magnets

MagnetsAnd Magnetic Fields

ReviewJust like Electricity, magnets work in FIELDS.

Fields are drawn with VECTORS

Review:Up, Down, Left and Right

ReviewWith Magnetism, we will need to look at vectors in 3-D.

How do we draw a vector arrow going into the page?

What would a real arrow look like going away from us?

ReviewKind of like this:

So we draw it like this:

ReviewWhat would a real arrow look like coming directly toward you?

ReviewLike this:

So we draw it like this:

MagnetismMagnetism works in a field, like Electricity.We use B for the magnetic field variable.

MagnetismMagnets work a lot like a PROTON and an ELECTRON.

Imagine a bar of metal with all the PROTONS on one end and the ELECTRONS on the other.+ + + + + + + + + - - - - - -MagnetismThe left side is positively charged, right side negatively charged and the field would look like this:+ + + + + + + + + - - - - - -MagnetismIf this were a magnet, there would be a North and South pole instead. Field looks the SAME+ + + + + + + + + - - - - - -NSElectricity and MagnetismElectricity and Magnetism are chained together.

E & MWhenever you have an ELECTRIC CURRENT, there is a MAGNETIC FIELD too, and vice versa.One is always quite larger than the other.

E & MEver had a power cord to close to a TV screen?

The distortion is from the Magnet Field around the cord.

E & MExample: Current vs. Magnetic Field in a power cord

LARGE currentSMALL magnetic field

E & MOther Examples:High Voltage Power linesBig VSmall BMRI MachineHuge VMedium BRefrigerator MagnetMedium BTiny V

Magnetic FieldsHow do we know what the Magnetic Field looks like around a wire with current in it?

Magnetic FieldsThere are some rules to help us.

They are called Right Hand Rules.

Step 1: USE YOUR RIGHT HAND!!

Right Hand Rule #1What does a magnetic field, B, look like around a wire?

Grab some wire with your RIGHT hand

IRight Hand Rule #1Make sure your thumb is going in the same direction as the current is!I

Right Hand Rule #1Your 4 fingers are lined up with the magnetic field. It goes in a circle around the wire.I

Right Hand Rule #1A field diagram would look like this:(Remember the vector arrows)Front Top BottomI

IIIRight Hand Rule #2What happens if we play with an electric cord in a magnetic field that was already there?

Right Hand Rule #2Well set it up like this:IN (+)S (-)Right Hand Rule #2Even without the wire, the magnets have a field already:N (+)S (-)BRight Hand Rule #2So what happens when the power is turned on? The wire starts moving! But what direction??N (+)S (-)BIRight Hand Rule #2Right Hand Rule #2 tells us in what direction the wire will be pushed N (+)S (-)BIRight Hand Rule #2STEP 1: USE RIGHT HAND!!!N (+)S (-)BIRight Hand Rule #2Index Finger points with B.N (+)S (-)BIRight Hand Rule #2Other three point with IN (+)S (-)BIRight Hand Rule #2Stick your thumb out. Thats the direction of the force (the way the wire will go).N (+)S (-)BIPracticeThe 2nd Right Hand rule will take some getting used to:#1- Index finger with B

#2- Other three with I

3#- Thumb gives you the answer

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