quarta-feira, 18 de abril de 2012

What the Heck am I learning in Science Class for Physics?

  WATTS up, guys! As you have read in the title (I hope), in this wonderful and marvelous post, I am going to talk about the things that I learned with my wonderful Science teacher, Ms. Silva (will you give me extra credits now?). In the beginning of our Physics class, my teacher gave me a worksheet with learning goals in them! And yeah I kind of have to use these goals in order to show you what I learned so far. There are 21 goals (OMG x0x), but out of 21, I'm only going to review 13 of them because I already reviewed the first eight goals one trillion times. Ok so prepare yourselves to see what I learned about...........ELECTROMAGNETISM! OOOOOOOOOOOOOOOOOOOOHH!!!! *0*

EM= electromagnetism (couldn't be more obvious? 0.0)

EM9. I can describe the properties and interactions of magnets.
-  The properties of magnets are:
  • That they attract iron or any material containing iron.
  • They can attract and repel other  magnets.
  • When a magnet is swinging freely, one part of it will always point north.
Now, about their interactions...well it is just like the interactions between electric charges. Like poles of magnets repel each other (north pole & north pole; south pole & south pole), while different poles will attract each other (north pole & south pole).


EM10. I can describe how the magnetic domains are arranged in a magnetic/non-magnetic material.
"Domains Before Magnetization"= domains of a non-magnetic material
-  In a magnetic material, the magnetic domains are aligned with each other and the electrons are spinning at the same direction, while in a non-magnetic material, the magnetic domains aren't aligned with each other and the electrons aren't spinning at the same direction. Okay guys, in this case, when people say that the electrons "spin" in the same direction, it doesn't really mean that they are actually spinning. The word "spinning" is used as a way to classify the kind of movement that the electrons are doing in a magnetic domain.


EM11. I can explain the connection between electricity and magnetism (electromagnetism).
This image is showing how an electric current can produce a magnetic field (check EM15 for more information)

-  Well for this I can say that electricity produces magnetism and magnetism produces electricity. This relationship is called "electromagnetism".


EM12. I can outline the difference between DC/AC current and its uses.
Lines represent the direction of the current

-  The difference between AC and DC current is that the AC (ALTERNATE current) current alternates direction, while the DC (DIRECT current) current moves in one direction. The AC current is used in transformers, in order to produce a magnetic field (don't know if you recall it, but electricity can produce a magnetic field 0o0) to induce the current to the second coil (INFO: Ever heard of electromagnetic induction? Well it's when you generate an electric current by a relative motion of a conductor of electricity going through a magnetic field - an electric current will be induced in the conductor; in other words, if  you also move the magnet/magnetic field through the conductor, an electric current will also be induced in the conductor). The DC current is used in series and parallel circuits, where the current moves in one direction, from the negative side of the voltage source to the positive side.


EM13. I can explain why the Earth behaves like a magnet and the consequences of it.
Earth's magnetic field
-   As you can see the Earth DOES behave like a magnet (oooooooooooooh!! *0*). This is due to the fact that there is a very hot solid center in the planet, that is surrounded by a layer of melted metal that flows at a certain rate, which produces an electric current that produces the Earth's magnetic field. Now the question that I have is...how can there be an electric current, if the center of the Earth is very hot? For the higher the temperature the more resistance there will be (if you are not understanding any of this electricity thing, than read the big mama post below...GOOD LUCK :3 <3), thus it will be hard for an electric current to flow through the metal. Oh but well it's Physics so anything can happen (just kidding! :b)!

  The consequences for the Earth behaving like a magnet are:
#2- Well it's something like this...
  1. The functioning of a compass for navigation, in which the needle of the compass will try to align itself with the Earth's magnetic field.
  2. The existence of a magnetic field that will protect the Earth from the solar wind by deflecting most of the charged particles that can strip the planet's ozone layer.
  3. Some animals, such as birds and turtles, that can sense the Earth's magnetic field, being contributed in their navigation during their migration.

EM14. I can explain the importance of grounding wires and using fuses/circuit breakers.
Grounding wires (any brown wire is a grounding wire 0.0)




Fuse

Circuit breaker

-  Their importance is to prevent the wire from burning up from the excessive build up of charges and to protect people from receiving an electric shock. And this is how they work: When there occurs a build up of charges in a wire, since the grounding wire connects the wire to the ground, the charges go directly to the ground, since there are many charges in it, which attracts the electric current.

  The fuse, when there's an excessive build up of charges, melts down, thus preventing the current from flowing. And the circuit breaker, opens/breaks the circuit, which also, stops the flow of electrons through the wire. A fuse can't be used anymore after it melts down, on the other hand though, a circuit breaker can, since it only opens instead of melting down, in order to stop the current.

EM15. I can explain how an electromagnet works and cite applications for them.
An electromagnet (don't need to tell you which is the coil and which is the magnet...right? 0.0)
-  An electromagnet consists of a coil formed by a conductor of electricity, with a ferromagnetic material in it. FYI ferromagnetic materials are materials with strong magnetic properties. And this is how an electromagnet works: there will be a current flowing through the conductor (in other words, it must be connected to a voltage source), and (again aiai -.-") an ELECTRIC CURRENT can produce a MAGNETIC FIELD. Because of that, the magnetic domains in the ferromagnetic material will try to align themselves with the magnetic field that is coming from the conductor. Thus all of them will be aligned at the same direction. Therefore, if you read EM10, an electromagnet is produced! A kind of MAGNET that is actually formed by the magnetic field of an ELECTRIC CURRENT! OOOOOOOOOOOOHH! *0*

EM16. I can explain how a simple motor works (parts and function). (<<you can always read my simple electric motor part in the post below...)
Although I said that the electrons will go from the negative side to the positive side...well, let me tell  you something...IT DOESN'T REALLY MATTER because we only CALL the sides "negative" and "positive", so the actual positive side of the voltage source can be the so-called "negative" side, and vice versa. The one thing that you should know is that the electrons will always leave from one side of the battery and go to the other side. And I think that this is the biggest caption that I ever wrote so far 0.0 Going to my personal Guinness! (...don't have one, 'kay? 0.0)

-   These are the parts of a simple motor: a voltage source, a commutator (split ring if you can see how it is in the picture, it is SPLITTED), an armature/coil, brushes, and a magnet.

  This is how it works:
  1. The electrons will leave the negative side of the voltage source, flow through the commutator, and go through the armature, through the other side of the commutator, and back to the positive side of the voltage source.
  2. The electric current (the flow of electrons) that is flowing through the armature will produce a magnetic field, which will try to align itself to the magnetic field of the magnet.
  3. Because of that, the armature, together with the commutator that is attached to it, will rotate.
  4. The current from each side of the armature will reverse, since each of the sides of the commutator that is attached to each of the sides of the armature, will receive a different current (the left side, through which the current was flowing away from it, that is now on the right side, will receive a current that will flow towards it. The right side, through which the current was flowing towards it, that is now on the left side, will receive a current that will flow away from it).
  5. Because the current reverses on each side of the armature, the magnetic field will again, try to align itself with the magnetic field of the magnet, and it will then rotate.
  6. And this process keeps repeating itself (unless anything that might prevent the motor from receiving voltage from the voltage source occurs).
EM17. I can describe how a generator and a transformer work.
AC (alternating current) generator! (<<the generator that I will be talking about!)

-  Contrary to the electric motor, a generator converts mechanical energy (motion), to electrical energy, and this is how it does it...WAIT, but before I need to say the parts of a generator:
  • A crank
  • An armature
  • A magnet
  • Slip rings (SLIP not SPLIT! Ò.Ó)
  • Brushes
FINALLY this is how it works:
  1. A person, or I don't know...SOMETHING will move the crank (the so-called mechanical energy).
  2. The armature, that is attached to the crank will rotate with it.
  3. Since the armature is located between two magnetic pole, you can say that it will rotate within a magnetic field. But unlike the electric motor, there’s no voltage source! So what happens?
          -Now here’s the thing: can motion produce electrical energy? The answer is yes (if you said no,  go study!). Have you ever heard of electromagnetic induction? It occurs when you generate an electric current through a relative motion of a conductor through a magnetic field (either the conductor can move through the magnetic field, or the magnetic field, through the current).

      4. Since the armature (the conductor) is moving in the magnetic field, a current is induced in it. The current goes in opposite directions in the two sides of the armature.
      5. Like the current in the armature of the electric motor, the induced current in the armature reverses after each half turn of the armature. Because after the two sides of the armature changes side, each side will receive an induced current going in the reversed direction, than their last current. The left side of the armature, through which the current was flowing away from it, that is now on the right side, will receive the induced current that will flow towards it. The right side of the armature, through which the  induced current was flowing towards it, that is now on the left side, will receive the induced current that will flow away from it (imagine that the electromagnetic induction is just like the voltage source, without the positive and the negative sides of course 0.0). Since the current changes directions, an AC current is produced (check EM12).
       6. As the armature turns, the slip rings turn with it. Like the commutator of the electric motor, the slip rings are attached to the ends of the armature and make contact with the brushes. These brushes, in which the slip rings, that receive the induced current from the armature, are attached to, can be connected to a circuit. Thus the generator becomes an energy source.

  OK! Now to the transformer! 




Step-down transformer
A transformer...just messin' with ya xD LOL


  A transformer is a device that increases or decreases voltage. It consists of two separate coils of insulated wire, wrapped around two sides of an iron core. Recall EM15 that there are coils of wire (the conductor) wrapped around a ferromagnetic material (yup, the iron alright!), which then, makes a transformer, an electromagnet! One coil of the transformer, that is connected to a circuit with a voltage source and alternating current, is called the primary coil, while the other coil, that is connected the a separate circuit that doesn’t have a voltage source, is called a secondary coil. And this is how a transferir works:

  1. The primary coil will receive the alternating current (AC). Since an electric current can produce a magnetic field, the AC in the primary coil will do that as well.
  2. The magnetic field will changes as the current alternates.
  3. Because this changing magnetic field is like a moving magnetic field through a conductor, a current is induced in the secondary coil (recall step 3 of the process of how a generator works).
  4. The secondary coil will transport the induced current to another circuit.
NOTE: A transformer only works if the current of the primary coil is an AC. If the current doesn’t keep changing direction, the magnetic field will also not change direction, and so, no current will be induced in the secondary coil. THEREFORE, a transformer WON`T work with a direct current (DC).

  Another thing that I want to add: Why is the iron core necessary in a transformer? The answer is to speed up the electromagnetic induction. Since the iron core will become a magnet (EM15), it will make the current induce to the secondary coil faster. It will kind of act like a fast transportation.


EM18. I can explain the importance of transformers to power grids.
Power grid
...Another power grid -.- (duh!)

  - Have you ever heard of a step-up and a step-down transformer?
   Like its name indicates, a step-up transformer increases something. And this "something" is the voltage. If the secondary coil has more loops, than the primary coil, than the voltage in the secondary coil will be greater. As you can see the electric current in a wire produces a magnetic field. Now, what will happen if you bend many loops in this wire with an electric current? Well you can see that the magnetic field in the new formed coil will be more concentrated, more powerful in other words. The more loops a coil has, the stronger magnetic field there will be in it. And this stronger magnetic field in the secondary coil, is what will induce a lot of current.
   Opposite of the step-up transformer, the step-down transformer decreases the voltage. Unlike the step-up transformer, in a step-down transformer, the secondary coil has less loops, than the primary coil. Therefore there will be less voltage in the secondary coil.

  So, what is the importance of transformers to power grids? The answer for that will be to control the voltage throughout the power grid.

  Step-up and step-down transformers are used in a power grid. Step-up transformers are used to speed up the rate in which the electric current travels to our homes so that we can receive convenient electrical energy. However when you increase the voltage in a transformer, there will be less current in its outcomes (since because of the increased voltage, the electrons will move faster, bumping more into each other). Then why do we still use step-up transformers? Well you can say that although there will be less current, the reduction of the current will only be small, so it won’t really drastically affect the speed of the current.

  Now step-down transformers are used to decrease the huge amount of electrical energy that gets to our homes, to a level that is usable, for if we were to to receive such huge amount of electrical energy, than our devices will burn up because they won’t be able to take it, since it’s too strong for them.

EM19. I can explain methods of power production and distribution.
  - Power can be produced by many energy sources: fossil fuels, nuclear, hydroelectric, biomass, solar, wind, and geothermal. This is how their energy is produced:
Fossil fuel plant
  Fossil Fuels: Fossils are burned, and the heat produced is used to boil water. The steam that is produced by the boiling water turns the turbine, which will turn the generator. Thus electrical energy is produced. In this process you can see that potential energy (fossils burning up) is converted into kinetic energy (steam produced to turn turbines and also, the produced electrical energy). Potential energy - the stored energy of an object at rest that can be used for motion (burning something to release energy, for example), while kinetic energy, which is kinetic energy, does involve motion (in the electrical energy’s case, the electrons push each other).


Ah, one of the disadvantages of fossil fuels is that it REALLY pollutes the air (see all of that freaking smoke?) and can contribute to global warming...LOLz I just wanted to add this picture, because I thought it was funny (got it from a good friend of mine :b). You get the pic?
  
  Nuclear: The nuclei of uraniums are broken apart and a huge amount of energy is released. This huge amount of energy is used to heat up water so that it can produce steam, which will then turn the turbine, which will turn the generator, producing electrical energy. Here, mechanical energy (nuclei being broken apart) is converted into electrical energy. Mechanical energy is also kinetical energy, for it involves motion.
Nuclear power plant


  Hydroelectric: A wall blocks the current of a river, building up huge amounts of water before the ball. The wall is then lifted up and a very strong current is released. The strong current turns turbine which are in the water. The turbines will then turn the generator, which will produce electrical energy. Again, mechanical energy (water turning turbine) is converted into electrical energy.
Hydroelectric power statioooooon!


  Biomass: Wastes (<<biomass) are burned, in order to heat up water, which will then produce a steam which will turn the turbine. The turbine will then turn the generator, which will produce electrical energy. Here, potential energy (biomass being burned) is converted into kinetic energy (steam turning turbine and the produced electrical energy).
Biomass power station

  Solar: Solar power cells are used to collect sunlight. which they will then covert into electrical energy. In this process, electromagnetic energy (light) is converted into electrical energy. Light is an electromagnetic energy because it stimulates the electrons, which will produce current.


Solar power plant

  Wind: Wind is used to turn turbines, which will then turn the generator, producing electrical energy. In this process,  mechanical energy (wind turning turbines) is converted into electrical energy.
Wind turbines!


  Geothermal: Geothermal  energy is what we can call energy from the earth; HEAT from the earth. In other words, areas from shallow ground to hot water or hot rock to a deep underneath the earth, where there is magma. From these areas, hypothermal fluids, which are stream are unleashed. This steam is used to turn the turbine, which again, will turn the generator, which will then generate electrical energy. Here, thermal energy (heat from the earth) is converted into electrical energy.
Geothermal power station!

  Now then, how is power distributed to devices? Well it can be distributed with two kinds of voltages: 110V or 220V,  and with different frequencies: 50Hz (hertz) or 60Hz. Hertz is the rate in which current alternates direction. Each kind of voltage and frequency is used in different places. But the two different voltages and frequencies aren't the same though. Between 110V and 220V, 220V is better, while between 50Hz and 60Hz, 60Hz is better, since the AC will be alternating direction faster; working faster - more convenient for devices.

EM20. I can describe the differences of 110V/220V and main advantages and disadvantages for each.
  -The differences between 110V and 220V are that 220V is stronger, than 110V, and unlike 110V, is used to power up devices that require more energy. The advantages of 220V are that it is stronger and devices that are for this 220V work better, since they will receive more power. The disadvantages, however, is if a person were to receive an electric shock, he/she would receive a much painful one (ouch!). The advantage of 110V is that if a person were to receive an electric shock, he/she would receive a less painful one. However, since its a weaker voltage, than 220V, then the devices that uses this kind of voltage won't work as well as the ones that require 220V.




EM21. I can describe the advantages and disadvantages of electrical energy.
ELECTRIFYING, BABY! (...ooookkkkkk forget what I just said... 0.0)

  -The advantages of electrical energy are that it is clean and cheap (ooooooooooooooh yeaaaaaaaaaaaaaaaaaah!). The disadvantages are that there is risk of injury (electric shock) and also, although the energy itself is clean, the way it is generated isn't and may harm the environment (fossil fuels and biomass burn things, which contributes to air pollution).