Electricity+and+magnetisim+2

We finally finished covering all of the goals for the unit of electricity and magnetism. I have to confess that for me it was very hard to learn them all but after doing A LOT of reaserch I can understand most of them and explain them pretty well. Here goes explanations and examples of the following topics: //Goals-// //**EM9. I can describe the properties and interactions of magnets.**// Before I thought a magnet was only that thingis that you stick on a refrigirator, it is but acctually... A magnet is any material that attracts iron and materials that contain iron. Magnets attracts or repel other magnets. In adittion, one part of a magnet will always point North when allowed to swing freele, or when no other magnetic field is close. The magnet has 2 sides the North and the South. The area around a magnet is known a magnetic field. Megnetic fields are invisible lines that map out the magnetic field around a magnet. Magnetic field lines spread out from one pole, curve around the magnet, and return to the other pole. This image shows the interaction between two magnets. When the North side is in touch with the South side the magnetic fields match and they attract and when the North is in touch with the North it repels.

//**EM10. I can describe how the magnetic domains are arranged in a magnetic/non-magnetic material.**// Magnetic fields of atoms in most materias point in random directions. This is bad because the magnetic fields cancel each one out almost entirly, causing a very week magnetic field. Although in magnetic fields of certain materials are aligned. A group of atoms that have their magnetic fields aligned is known as a magnetic domain. In a magnetized material most of the magnetic domains are in the same direction, in other words they are alligned. After magnets the magnets can be either temporary wich is one that easily losses its magnetism and a permanent magnet wich keeps their magnetism for a long time. //**EM11. I can explain the connection between electricity and magnetism (electromagnetism) /**// **EM15. I can explain how an electromagnet works and cite applications for them.** Whenever there is electricity, there is magnetism. An electric current produces a magnetic field. This relashionship is called electromagnetism. An example of this is a compas. When no current is present, the compass needles points North (magnetic North). When you add a current, the compass needles align with the magnetic field produced by the current in the wire. So you can create a magnetic field with a current and a magnet and a magnetic field can also induce a current.



This images show that if there is a magnetic field close to a compass the compass will point North towards the magnet North. The other image show that if there is no magnetic field close the compass wil work normally. A good thing to look is that the magnetic North of the ears is actually the geographycal south.

A //Solenoid// with a ferromagnetic core is an electromagnet. If you place a ferromagnetic material (which is things such as iron) inside a solenoid, the strenght of the magnetic field increases. A solenoid is a coil of wire with a current. The increase in the magnetic field occurs because the ferromagnetic material becomes a magnet. So resuming all these ideas an electromagnet is a magnet that can be turned on and off. You can easly increase the force of an electromagnet. Examples of how you can increase is by increasing the current in a solenoid, add more loops of wire to a solenoid. Also put the loops of the coil together. When I was doing my motor together with my dad he told me to put the round part (armature) with perfects loops close to each other so it could spin better. Electromagnets have a very good utility in our lifes. Electromagnets can be used to rise very heavy objects. For example in a car jump cars can be lifted by an electromagnet. The machine is turned on creating a very strong magnetic field and attracting the car and when you need the car to be dropped you turn the machine of turning the current off resulting in the loss of the magnetic field. This is a good and easy representation of what is a electromagnet. You need a magnet and a current. And you can easily increase it by increasing the current in a solenoid, add more loops of wire to a solenoid. Also put the loops of the coil together. Also it can be easily turned of you just take the battery away.

//**EM12. I can outline the difference between DC/AC current and its uses.**// A DC current is the abriviation for Direct Current and AC current is the abriviation for Alternating current. In an induced current, charges may flow in one direction only or they may alternate directions. To understand the diference between DC and AC currents here we go!



A current that flows in one exact direction only is called a Direct Current. DC can be induced from changing the magnetic field or produced from any source of energy such as a battery. When a battery is placed in a circuit, charges flow away from one end of the battery, around the circuit, and into the other end of the battery simuntunesly.



Now if you move a magnet up and down rapidly in a current you create an Alternating Current. The currrent in the wire would inverse as well. AC consists of charges moving back and forward in a circuit. Most places around the world use alternating current. This is because it is better. The AC current can be easily raised or lowered, in contrary to a DC. This means a high voltage can be used to be send energy to far away places. When the current gets close to our homes it can be reduce easier for our use. A device used to alternate a current in a motor is the commutator.

We can easily compare the Earth to a magnet because just like a magnet the earth has a magnetic field surrounding it and has a South and a North pole. This related to the topic I brought up before of how a compass works. The poles of the magnetized needle align themselves with the Earth’s magnetic field. The explorer who discovered that the earth is like a magnetic field is called Sir William Gilbert. In geography class I was teached that the North is up and the South is down. This is acctually only geographically speaking but scientificly speaking the earths North is down and the South is up. Some consequences of this is since the Earth created a storng magnetic field, earth itself can make magnets out of ferromagnetic materials. Also the Earths magnetic field affects the movements of electrically charged objects in space. The region of Earths magnetic field is shaped by the solar wind is called a magnetosphere. Other consequences are Auroras Burials. When high speed, charged particles get close to the Earths surface, they interact with atom in the atmosphere. This causes the atoms to give lights. This is what is called an Aurora. The grounding wires are used for our safety. They are used to prevent short circuits. A short circuit is a connectioc that allows current to take the path of least resistance. For example the current can run trough a person instead of going trough the wires. This can cause some electrical shocks. The way for us to protect us is to provide an alternating path for the current. A circuit can be grounded when charges are able to flow directly from the circuit into earth in the event of a short circuit. There are different ways of grounding and one is a third prong. This third pong connects metal pieces of the appliance to the ground wire of the building. If a short circuit happens the electrical energy will flow directly to the Earth.
 * EM13. I can explain why the Earth behaves like a magnet and the consequences of it.**
 * EM14. I can explain the importance of grounding wires and using fuses/circuit breakers.**

To prevent the circuits from getting to hot, devices called fuses and circuit breakers are added to the circuit. A fuse is a device that contains a thin strip of metal that will melt if there is too much current trough it. A circuit breaker is a reusable safety switch that breaks the circuit when the current gets to high. Circuit Breakers are easy to reuse.

The parts and functions of a motor are this:
 * EM16. I can explain how a simple motor works (parts and function).**

Brushes: small parts that gently “brush against” the commutator, allowing the current to flow into it and out of it. Commutator/ split rings: is attached to the armature and spins with it; is responsible for reversing the current every half a spin Armature: Piece of ferromagnetic material that spins repeatedly and creates mechanical energy. It will become an electromagnet upon spinning occurs.

Here goes a vidio of how a motor works: [] A generator is a device that transforms mechanical energy into electrical energy. It does the inverse opperation of a motor. A generator uses motion in a magnetic field to produce an electric current. There is two types of generators just like there is two types of current. The AC generator works like this; as a crank is turned, the armature rotates in the magnetic field. One side of the armature moves up, and the other side move down. The up and down motion induces a current in the wire. The current is in opossite directions on the two sides of the armature. After the armature turns halfway, each side of it reverses directions in the magnetic field. The current in the wier echanges direction as well. The result is an alternating current. As the armature turns the slip rings also turn. The slip rings are attached to the ends of the armature. As they turn, they make contact with the brushes. The brushes are connected to the rest of the circuit. And this is how a genarator becomes an energy source. The DC generator is similar to the AC generator. The only difference is instead a slip ring it has a commutator. Many generators are used in power distribution. But instead of the crank they use huge turbines. We have many good ways of distributing energy but a transformer will make the energy good to use in our homes. A transformer is a device that increases or decreases voltage. A transformer consitst in two seperated coils of insulated wire wrapped arounf in a iron core. There is the primary coil and the secondary coil. The primary is connected to a circuit with a voltage source and alternating current. The other coil, is connecte to a separate circuit that does not contain voltage. There is twon types of transformers, the step up and the step down. The step up increases the voltage, where the secondary coil has more loops than the primary coil. The step down transformer decreasses the voltage, the primary coil has more loops than the secondary coil. They are very usefull to transmit energy to far away places. Power grids are very important so that we dont lose to much energy in form of heat, we need to distribute energy in high voltages for homes far away. The problem is that this energy cant be so high when it gets to youre house or it can damige your appliances.
 * 1) Once the battery is connected to the motor, a circuit is created as it becomes closed; this causes a current to form. It flows through the brushes, in the commutator, around the armature, back through the brushes and back in the battery.
 * 2) When the current flows through the armature, the armature becomes an electromagnet (since it is surrounded by permanent magnets). This causes it to have a magnetic field around it. The magnetic field of the side of the armature that is taking the current back to the battery interacts to the South side of the permanent magnet; the magnetic field of the other side of the armature interacts with the North side. The North side pushes that side of the armature, causing it to turn.
 * 3) Once it spins halfway, the commutator comes in contact with the brushes from the side that is taking the current away from the battery; this causes the current to reverse: this side of the armature is now taking the current away from the battery instead of towards it. As this change of current occurs, the North side of the magnet interacts with the magnetic field of this side of the armature and pushes it and makes it spin. This cycle repeats non-stop, causing the armature to spin continuously which creates the desired mechanical energy.
 * EM17. I can describe how a generator and a transformer work.**
 * EM18. I can explain the importance of transformers to power grids.**

There is always an energy source transformed to eletrical energy so we can use.This is the job of the generator. Here goes the main forms of producing energy and their advantages and disadvantages.
 * EM19. I can explain methods of power production and distribution.**

__Fossil Fuels__: Chemical -> Electrical: Polutes __Nuclear Energy__: Chemical -> Thermal -> Mechanical -> Electrical: Might be dangerous because if the cooler doesnt work a lot of radiation goes out and might kill the enviorment. Other wise if it works it is really good because it produces A LOT of energy. Many coutries are affraid of happening what happened in chernobyl and in japan so they are using this type of energy less. Another disadvantage is that it has to be close to the ocean so you have enough water to cool down the uranium. __Hydroelectric__: Mechanical -> Electrical: This type of energy is my favorite because it is very good. The advantages of a hydroeletric is that it is ecofriendly. I does not kill any fishes because they actually build a stair so fishes can ovulate. Also it produce a lot of energy and it is cost beneficial. __Biomass__: Chemical -> Thermal -> Mechanical -> Electrical __Solar:__ Electromagnetic -> Electrical: Only disadvantage is that you can only have energy if there is sun, so in antartica it would be impossible to have solar energy. Also it doesnt produce much and is very expensive. __Wind:__ Mechanical -> Electrical: Kills birds but doesnt damage the envierment. The problem is that it takes up to much space. __Geothermal__: Thermal -> Mechanical -> Electrical

The advantages of a 110v is that is less dangeroues it there is a problem. The disadvantage is that it is not Cost Efficient because you can lose more energy in form of heat. The advantages of a 220v is that costs less and is cost efficient. The disadvantage is that is more voltage so if anything that goes wrong the shock is bigger.
 * EM20. I can describe the differences of 110v/220v and main advantages and disadvantages of each.**

The advantages of electrical energy is that is easy to transport and easily controlled. It is very rare to have people dying because of electrical energy. Also it is easy to be converted for exaple into a motor. The disadvantages of electricall energy is that if not well planed it can be dangerous and it may be a polluting source like a fossil fuel.
 * EM21. I can describe the advantages and disadvantages of electrical energy.**