Final Unit Blog Reflection.

         
 It's finally that time of year: our final unit blog reflection! It's hard to believe that the year has gone by this fast. And we certainly ended on an interesting unit to talk about. In this unit, we talked about magnetism, magnets, north and south poles, compasses, cosmic rays, the "right hand rule", motors, the necessities of making a motor, electromagnetic induction, generators, and finally transformers. Also, some big questions that we answered were why do paperclips stick to magnets, how are the northern lights created, what makes a motor work, and finally, how do credit card machines work.
     
We first started off by talking about talking about magnets and magnetism. Remember, moving charges are the source of ALL magnetism. This concept is key to remember. Generally, electrons tend to spin in random directions; a cluster of these electrons moving together is called a domain. Before magnetism occurs, there is no net direction. However, when something comes into contact with a magnetic field, the domains will align in the same direction as that magnetic field. This net direction makes forwards and backwards distinguishable; these are called poles. The magnetic field inside of a magnet will run towards the north pole and runs away from the south pole. The magnetic field also surrounds the magnet and goes around from north to south. Like poles repel each other and opposite poles attract each other because of the field lines. Attraction is caused by the field lines running in the same direction and repulsion is caused by field lines pointing towards each other. We already know that compasses point north, but because of the knowledge we just acquired, we know that the compass needs to be magnetized for this to happen. Now, lets talk about why a paper clip will stick to a magnet. Originally, the domains in the paper clip are random. The magnet has a magnetic field. When the magnet comes close to the clip, the domains of the paperclip align to match the magnetic field of the magnet. The paper clip now has a north and south pole. The north pole of the paperclip is attracted to the south pole of the magnet. Thus, they stick together.
       
 The next thing we talked about were the northern lights. What this really is are cosmic rays- which are charged particles entering in the atmosphere. As we know, there is a magnetic field running around the earth. When the charged particles try to enter perpendicular to the magnetic field, they will feel a force that prevents them from entering the atmosphere. However, when the particles try to enter through the poles, they enter in a parallel fashion which will mean they feel no force. Thus, northern lights only occur at the poles. However, this means that people there have an increased risk of cancer because the cosmic rays can rip holes in the DNA. Now, lets talk about the affects on wire. Wires have a magnetic field. We can now where this magnetic field points thank to the right hand rule. If you point your thumb in the direction the current is running, your hand should then signify the way that the magnetic field wraps around the wire.

 Next, we talked about motors and even got to build one of our own. We learned that for a motor to work, it needs to have a current carrying wire and a magnet. For my motor, I used a battery, a coil of wire, a paperclip, and a magnet. We use the battery to carry the current. The coil of wire was our current carrying wire. Finally, the paper clip was used to complete the circuit and the magnet provided the magnetic field. Ultimately what happened was the loop of wire turned on top of the battery. This happened because the current carrying wire felt a force in the magnetic field from the magnet. The force the loop feels will cause a torque. This torque will cause a spin. You are turning electrical energy into mechanical energy. This running motor can be used to make a car, a fan, or a blender.

 One of the bigger topics we learned about was electromagnetic induction. We learned that this is when you have a loop of wire and a complete circuit. When you insert a magnet through or around the loop of wire, this causes a change in the magnetic field of the loop. This change ultimately induces a current. Now that we know about this, we can learn about why a traffic light changes when you reach an intersection. In the pavement, there is a loop of wire. On the bottom of your car there are magnets. As the magnets pass through the loop of wire, it changes the magnetic field of the loop. This change in the magnetic field induces a current in the wire. This current acts as a signal to the stoplights that a car has reached the intersection and the light needs to turn green. We can also learn about a generator. When the magnetic field of an object is continuously changing, a generator is made. The generator turns mechanical energy into electrical energy. This will work because the electrons are perpendicular to the magnetic field. This differs from a motor, because a motor turns electrical energy into mechanical energy and the wire must feel a force.

 Finally, we learned about transformers. Transformers are made up of two wires, the primary coil and the secondary coil. The powers are the same in these two coils. The number of turns the coils make is directly proportional to the voltage induced. The more loops there are, the more voltage will be induced and the less coils there are, the less voltage will be induced. AC current will cause the magnetic field to change in the primary coil because AC current runs in the primary coil. AC current runs through transformers. It is important that transformers use AC because otherwise a change in the magnetic field will not occur.

 Personally, I have felt that this unit has been relatively easy. The only thing I initially had a hard time with was learning how a motor worked. But after actually making a motor it made a lot of sense. I am a very visual person and it has been nice to do various experiments in this unit. Otherwise the material has seemed very straight forward to me.

 I feel that my efforts to class and homework have, if anything, slightly increased this semester. I find myself more attentive in class and have felt that as a result my quiz scores have improved. I only hope that this will reflect on my unit test tomorrow. It always seems that I am fine throughout the unit but the day of the test I become overly stressed and end up not doing as well as I could. I do think that my persistance in class this unit has helped me. I still also feel like I take advantage of conference period when I need it. My confidence has also improved because when I answer questions I feel much less stressed out and much more at ease. Ultimately, my goal is to end this school year with a bang. I want to try my hardest on the final exam and get great results for my final grades. I plan to study all the material and take advantage of the review. Hopefully, the material from last semester will come back to my brain. I will try my hardest and ultimately that is all I can do.

I am officially a mechanic

I always thought that creating a motor would be so complicated and only graduates of MIT would be able to achieve this. However, physics class today definitely proved me wrong. I can officially say that I have made my own motor that worked for more than thirty seconds. Now, I'm not saying I'm some sort of genius mechanic, but I do know everything that is involved in making a motor run. Here are the few simple concepts I needed to understand to create a small, running motor. The four things that were essential to the creation of my motor where a battery, a coil of wire, a paperclip, and a magnet. Before I go into detail about what these different items do, I want to remind everyone what we said a motor was. In class, Ms. Lawrence said that a motor was made of a current carrying wire and a magnet. Now that we know this, let's figure out what the purpose of all the items listed above have in the motor. First off, the battery is what carries the current. The coil of wire is what carries this current. We attached two paperclips that were bent to the sides of the battery. These batteries are what completed the circuit from the coil of wire to the battery. Finally, we attached a magnet onto the battery and close to the coil of wire so that it would provide a magnetic field. Once we attached the two bent paperclips to the side of the battery with a rubberband, we needed to create a coil of wire. I wrapped the wire around the paperclip to give it an oval-like shape. Once this coil was created, we needed to do something very important, scrap the plastic coating off the coil loop. We needed to scrape the plastic off because the current would not have been able to go through the coil, and then our motor would not have worked. One of the key things we learned before making the motor was a special hand sign that is illustrated in the picture above. The index finger points in the direction that the current flows. From there, your thumb signifies the directional force and your middle finger represents the magnetic field. This is totally dependent on which way the current is. Based on this hand rule, we knew that our magnetic field would be down below and perpendicular to the current, and then our thumb would be pointing out. The magnet is ultimately what causes this magnetic field. Thanks to our own physics hand sign, we could figure out the directional force and the magnetic field. Thus, we know the current carrying wire will feel a force in because of the magnetic field. The force that this loop feels will cause a torque. This torque will cause a spin. Ultimately, in this process we are turning electrical energy into mechanical energy. So, that is how I, Anna Hart Bassett, built my own motor. There are many things that I could have done with this tiny creation. I could have added wheels to the end and built a small car. I could have attached some fan blades and created a cool fan to use during the hot summer days. However, my personal favorite option is to add some blades to the motor, add some ice cream, milk, and fruit, and create delicious smoothie. It certainly would have been a tasty treat after creating my motor. While there were no smoothies had in class, I did get to keep my wire coil to remember my working motor.

Back to the Basics: Learning About Magnetism with the Science Guy

*the embedding was disabled for this video so here is the link* http://www.youtube.com/watch?v=ak8Bh9Zka50 I know that everyone from our generation will remember watching Bill Nye the Science Guy videos in our elementary school classes. He has a great way of explaining something in simple terms and this is no different today. The attached link is a video that has clips from Bill Nye's episode on magnetism. Not only does Bill reference the north and south pole, as we discussed in class, but also talks about what kinds of things have magnets in them. I personally think it was very helpful to hear about magnetism in the simplest terms. I hope it works for you all as well.

Coming Down the Home Stretch

Another unit has come and gone, but this one has gone on particularly long because of spring break. We took a short break about half-way through the unit, so it might cause some complications for the test tomorrow, but I guess we will see. In this unit we learned about charges, why our hair sticks up when we put on a sweater, why ser, how lightning is created, conductors, insulators, polar, coulomb's law, electric fields and shielding, electric potential energy, voltage, the different kinds of currents, why CFL's are greener than incandescent light bulbs, and why a fuse blows when multiple appliances are plugged in at the same time. To start off, we learned about charges. We know that positive charges are called protons and negative charges are called electrons. When there is an even amount of positive and negative charges in an object, then it is considered neutral. However, when there are more negative charges, the object is negative and vice versa. Opposite charges attract each other whereas like charges repel each other. There are three ways we learned to charge and object. These three ways are by direct contact, friction, or the process of induction. We use these ways to charge an object to explain why our hair stands on end when we pull a sweater over our heads. The sweater rubs against your hair and therefore steals electrons. The sweater most likely becomes negatively charged and likewise the hair most likely becomes positively charged. Because the positive charges want to repel each other, your hair stands up on end to get away from itself. Next, we learned about lightning, how it is produced, and how a lightning rod protects a house from being struck by lightning. Lightning is created when the clouds are charged through friction. The ground is positively charged, and therefore the negative charges from the clouds will attract the ground while the positive charges from the clouds will move away. The negative clouds and the positive ground will eventually attract each other so much that lightning builds up. We learned that lightning moves up and not down. Lightning rods are tall pointy tower that are on top of your house and then run along the sides of your house into the ground. The lightning is attracted to the pointy end of the lightning-rod and will therefore hit it. The energy from the lightning is then directed from the rod, down the side of the house and into the ground. Following this, we learned about conductors and insulators, polarization, and Coulomb's law. A conductor lets a charge move through it whereas an insulator stops the charge from moving. That's pretty simple, but polarization takes things up a notch. When something is "polar" it means that the charges separate and go to the opposite sides of an object. However, the object will still be neutral as long as there are the same amount of protons and electrons. Now let's apply this to using seran wrap. Seran wrap is negative. When it reaches the bowl, the negative electrons go to the wrap and the negative electrons move away. The bowl is now neutral and polar. Another law we use to describe this is Coulomb's law; this law states that the force between any two objects is inversely proportional to the distance. Therefore the farther away something is, the less the force. The equation for this is Kq1q2/d^2. Looking back at the seran wrap example we see that the distance between the attractive charges is smaller than the distance between the like, repelling charges. Thus the force will be greater between the bowl and the attractive forces will be greater than the force between the like, repelling charges and the bowl. Next, we learned about electric fields and shielding. We defined an electric shield as an area around a charge that can push or pull another charge. The negative charges will be pushed out and the positive charges will be pulled in. THe field lines of and electric field indicate how strong an electric field is; when the lines are closer together, the electric field is munch stronger. We then discussed circuit boards to move onto shielding. We learned that a circuit board needs all atoms to be in their proper place. When a negative charge is surrounded by positive charges, the negative charge will feel no force acting on it because the charges counteract each other. It doesn't matter the negative charge's position in the sphere. This is called electric shielding and this helps keep electronics safe. Next, we talked about electric potential and electric potential energy. Electric potential is also known as voltage, and is represented by PE/q; q stands for charge. The electric potential energy is the potential energy of charges. This occurs in like and unlike charges. Most importantly, we learned about the relationship between resistance, current, and voltage. Current is the energy that runs through a circuit and resistance is how easy it is for current to run through this circuit. Based on various experiments we did in a lab, we learned that current and voltage are directly related whereas resistance and current are inversely related. We show this by the equation I=V/R. Finally, we learned about DC and AC, why CFL's are greener than incandescent, and the difference between series and parallel circuits. DC stands for direct current and ac stands for alternating current. The difference between CFL's use less wattage with the same amount of brightness. Finally, we learned about series and parallel circuits. When more appliances are added to a series circuit, the resistance increases and thus the current decreases. However, in a parallel circuit, when more appliances are added, the more the current is, thus decreasing the resistance.

Blast From the Past: CDD

This is a picture from CDD when I was helping my friend Zan get ready. I'm pretty sure we used about five different appliances from hair straighteners to phone chargers. Thankfully, we did not experience the circuit breaker trip, but this tends to happen during dance times because so many electronics are plugged in. Lawrence dormitory is wired in parallel which is what most things are wired in these days. A parallel circuit insures that multiple appliances can be plugged in and all of them can work with a large amount of energy. The more appliances plugged in, the more current that will be produced. This can cause a problem when there are too many appliances causing too much current. This is where a circuit breaker or fuse comes in handy. Both these items shut off the power supply when it detects that there is too much energy. It is attached to an area where the power source flows to all of the different appliances. It is wired in a parallel circuit so that it will cut off the power supplies without anything remaining on. While this might be frustrating when it initially happens, this method prevents electrical fires, so, in the long run, it is extremely beneficial.