UNIT 7

Hey wanna know something that's really attractive?......  MAGNETS!!!!!    

Yup, were gonna talk about magnets today.  

A magnet is an object that has its domains aligned in the same direction.   Well what are domains? 

Great question, domains are caused when the electrons in a certain area spin in the same direction.                                                                                                                                                                          

                     Aligned Domains = magnetized          Unaligned Domains = Not magnetized 

                       

Because a magnet has its domains all in the same direction, a magnetic field with a specific direction is present in and around a magnet.   Inside the magnet the field flows from south to north.
 But outside the magnet the field begins to turn around and flow from north to south.
The symbol used for magnetic field is 'b'. 

                                

The Earth also has a magnetic field just like a magnet.  Except the only confusing this about this is that the earths geographic north, is the magnetic south.  That is just silly in my opinion, and i think that whoever named the geographic north and south owes us an apology.   

The magnetic fields on Earth are responsible for some of the most amazing natural phenomena called the Northern lights. The Earth is constantly being bombarded by cosmic rays.  And most of the time theses rays are deflected back into space my the Ezarths magnetic field because they are moving perpendicular to the field.  However, at the poles some of the rays are not deflected by the magnetic field and make it into the atmosphere.   This results in a beautiful light show.  

               Electromagnetic induction: Ok,  what is that?      Glad you asked.
Electromagnetic induction is when the magnetic field of a non current carrying wire is disrupted.   What this causes is a change in voltage and potential energy which induces a current.  
This is a principle that we see everywhere.  At stoplights, credit card machines and metal detectors to name a few.

                        

All of this is based off of Michael Faradays's Law which tells us that when a magnetic field changes a voltage is caused.  And this discovery is the reason why teenagers are able to bankrupt their parents with the swipe of a card.


                                                       Motors  vs. Generators
Motors and generators are very similar in that they both use magnets and coils of wire.  Where they differ is what they produce.

A motor takes electric energy and turns it into mechanical energy by using a current carrying wire to feel a force and generate a torque.   This torque can be used to turn anything form the wheels or an RC car, to a hand mixer.

A generator turns mechanical energy into electric energy by having magnets spin over coils of wire (or vice-versa).  This is able to generate electric energy because when a magnet passes by a coil it induces a current.   This is the basic principle that we get our daily electricity from.  


            But what do you do when there is either to much or to little voltage flowing to your device?
WOW,  you are just full of great questions today.    Well the answer to that question is something called transformers.   Transformers at its most basic level are two different stacks of coils with varying numbers of loops depending on whether it is a step up, or step down transformer.
 
                    
This one above is a step up transformer because there are more loops in the secondary coil than in the first.  This means that the secondary will have a higher voltage.  
But wait, how can they have a current of voltage or any of that stuff if they are not touching?
Wow I should give you a medal because you ask just the most relevant questions.  :)
Well the answer to your question my friend is induction.  By using AC current the primary wire induces a current in the secondary wire without even needing to touch it.  Cool huh?