Test Alert!

Yes test alert! Which means we are having a test very soon. Next week Tuesday 28, we are having a test. We have almost completed this chapter and are moving on. As Mr. Chung said, our tests will be about four questions, but beware, these are four difficult and time consuming questions. Preparation is mandatory in order to receive an excellent mark on this test. So study study study! Also today in class we had a work period to complete unfinished work, which was very useful because I was able to complete almost all of my assignment, which is due this Wednesday, don't forget! We are also advised to take ten points from the book from pages 582-589. So here it goes.

• Magnetic field is the distribution of force in an area of the magnet. There are two magnetic characteristics, north and south, which control the force of the magnet. In other words, opposites attract each other. If you have ever tried to stick two magnets together and you can feel a force between them that will not allow them to come together, it is because you are trying to attach north and north or south and south together.
  
• Ferromagnetic metals are magnets that attract certain metals and are not magnets. These metals include iron, nickel, cobalt or a mixture of the three.
  
• The domain theory of magnets states that ferromagnetic elements have an atomic structure that makes them strongly magnetic. Magnetic materials are made up of a lot of smaller magnets.
  
• The textbook definition of domain theory is that all large magnets are made up of many smaller and rotatable magnets, called dipoles, which can interact with other dipoles close by. If dipoles line up, a small magnetic domain will form.
  
• Oersted's principle: Charge that is moving through a conductor produces a circular magnetic field around the conductor.
  

• Scientists have come up with an easier way to predict the direction of the electromagnetic force from the current. This is called the right-hand rule because it involves using your right hand. There are three right-hand rules.
  (Right-hand rule # 1,2 are written in tomorrow's blog because we have a lesson on it in class tomorrow, so check that! However here is right-hand rule #3)
  

1. Right-hand rule #3 for conventional flow, the motor principle: Open the right hand so that your fingers are in the direction of the magnetic field. Your thumb should point in the direction of conventional flow. The palms show the direction of the force produced.
   

• Demagnetization is the process of ferromagnetic materials become demagnetized.
• Reverse magnetization is when polarity is reversed.
  
• It is proven that a magnet has a limit as to how much it can become strong. Once it has reached its limit, it will no longer be stronger that what it already is.
  
• Magnetic induction is when ferromagnetic materials can be magnetized. An example of this would be when the Earth does this to train tracks, steel and girders.

Make sure to study for the test on Tuesday because it is our first real mark. Good luck!

-Peggy.