Unit 7 Reflection

 In this unit I have learned about charges, magnetic fields, electric fields, magnetism, magnetic poles, electromagnetic induction, generators, transformers, and how motors work. 

   The most important thing you need to know about charges is that the main source of magnetism is moving charges. All charges have electric fields in them, but only moving charges have both magnetic and electric fields. All objects have something called a domain. A magnetic domain is the direction in which the electrons in a magnetic field are going. When the electrons are all going in different directions, the object that contains the magnetic field is not magnetized. When they are all going in the same direction, however, there are poles which means that the object is magnetized. Magnetic fields flow from south to north. This means, that inside the magnet, the electrons flow upwards. Outside of the magnet, however, the magnetic field lines are the opposite. They flow from north to south. 

     The magnetic field of the earth is the opposite of what you think it is. We call the pole near antarctica the south pole and the pole where "santa claus" supposedly lives the north pole. It is true, these are the correct names of the magnetic field lines. However, the actual "magnet" that is inside the earth has the north pole at Antarctica and the south pole near santa claus. The reason that this is the way it is is because we only feel the force of the magnetic field lines around the magnet, not the magnet field inside the magnet itself. 

     Have you ever stuck a paper clip to a magnet, and wondered why it sticked? Paper clips are not magnetic, however, there is a way to magnetize them. A paperclips electrons are all flowing in different directions. The magnetic field of a magnet, however, pulls the magnetic domain of the paper clip towards its north pole when the paper clip is touched to the magnet. Because the magnets and the paper clips domain are in the same direction, the electrons are all flowing north. Therefore, the paper clip sticks and becomes magnetized. 

     When a charged particle is perpendicular to a magnetic field, the field repels it with maximum force. When a charged particle is parallel to a magnetic field, however, the particle joins the field without feeling a force. The easiest way to think about this is to think about the earths magnetic field and cosmic rays. Most everyone knows that the people who live on the poles are more susceptible to diseases caused by contact with cosmic rays. This is because the particles are parallel with the magnetic fields at these poles, and therefore feel no force (meaning have no trouble) entering the magnetic field of the earth.

      Electromagnetic induction is simply the process of putting a magnet through or around a series of loops of wire to generate a current or induce a voltage. The way that it works is, when you move a magnet over a wire, it changes the magnetic fields of the loops of wire and this change induces a voltage which causes a current. Believe it or not, this concept is used in our everyday lives. A car is a magnet, and the pavement has wires underneath, and this is how stop lights know if a car is waiting. Your credit card has magnets, and the machine has wires, and that is how stores know what your credit card number is. 

    Generators use electromagnetic induction to induce a voltage and create a current. They use mechanical energy in and get electrical energy out. This is because they simply have to crank something which moves magnets over a coil of wires and this movement causes a change in the magnetic field which causes a current.

     Motors are the opposite of generators, because you put electrical energy in and get mechanical energy out. We made a motor in class. We did this by using the concept of a motor and applying it to a battery, a coil of wire, two paper clips, a magnet, and two rubber bands. We did this by first bending the paper clips to make them capbaple of holding the coil of wire above both the batter and the magnet, and touching both sides of the batter in order to be able to carry the current to the wire. Then we wrapped rubber bands around the battery so that the paper clips would stay. Next, we put the magnet on the battery on the top in the middle. After that, we did the most important part. We wrapped the wire into an ovular coil that had about one inch of extra wire on each side. Then, we scraped the top (and only the top) of both wires. The scraping part is probably the most important part of the whole motor. This is because when the wire is carrying current, the magnetic field of the wire changes because of the magnet, and the electrons in the wire feel a force. The force is the greatest force possible because the coil of wire is perpendicular to the magnetic field of the magnet. This force causes a torque, which causes the coil to spin. Because the wire does not get current at all sides, and only on top, this happens over and over again. Then, you can attach a fan blade, the blade of a blender, or even wheels. This is how all motors work. Seems pretty simple, doesn’t it?

     The next and last thing we learned about was probably also the most complicated. It is a thing called transformers, and like all the other things we have learned about in this unit, it is used in our everyday lives. Transformers are simply a large coil of wires and a small coil of wires that, depending on which size is first, can either increase or decrease the voltage given to an appliance or a house. Transformers can also be used for computers, cell phone charges and many other appliances. Transformers use alternating current in order to change the voltage in the ways needed. They would not work with direct current. There are many transformers in the power lines to our houses. They have high voltage so that when they give power to our house, it is easier to reduce the voltage and increase the current. The way you figure out how many loops or volts are in the primary or secondary coil of wires is through the equation primary # of loops/primary voltage= secondary # of loops/secondary voltage.
     What I have found difficult about what we have studied is all the different points you have to make when answering each question. I overcame these difficulties by practicing answering each question a lot of times and thinking about the different concepts in relation to each other. My problem-solving skills and effort this unit have been pretty good over all. I have done all my homework and tried to study for each quiz that we had. I think my groups podcast this unit was one of our bet and we all collaborated really well with each other. My goals for the net unit is to try to rely less on what we learn in class and I plan to achieve this by paying more attention to the reading.
     I can make tons of connections to the real world from this unit because everything we studied can be connected to our everyday lives. Credit cards, car motors, security at airports, and even stop lights can all be connected back to these physics concepts.