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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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.


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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