More Goals for EM Forces

I have already posted an explanation of goals 1-8. Now, goals from 9-21 follows:

EM9: I can describe the properties and interactions of magnets.

A magnet is a material made of pure iron, nickel, cobalt, or materials that contains iron, nickel, or cobalt that is able to attract or repel them. Magnets interact in a simple way. To understand, you need to know the definition of a magnetic pole, which is the two ends of a magnet, no matter its shape. Therefore, magnetic poles that are alike repel each other, differently from unlike magnetic poles, which attract each other.

EM10: I can describe how the magnetic domains are arranged in a magnetic/non-magnetic material.

A magnetic domain is an area within a magnetic material (iron, nickel, cobalt) which has a magnetization within range. This means that all atoms will be lined up in the same direction. The direction that domains point determines if the material is or isn't magnetized.

Observe:

. Non magnetized material: magnetic domains point in random directions.

. Magnetized material: magnetic domains point in the same direction.

EM11: I can explain the connection between electricity and magnetism (electromagnetism).

Electromagnetism is the relationship between electricity and magnetism. What produces a magnetic field is an electric current. The force of a magnet when near a conductor can create also create current.
Watch an explanation o electromagnetic waves in the video that follows:
http://videos.howstuffworks.com/science/electromagnetism-videos-playlist.htm#video-27962

EM12: I can outline the difference between DC/AC current and its uses.

AC stands for alternating current, as DC stands for direct current. In an alternating current, charges flow back and forth in a circuit, differently from a direct current where charges in only one direction. There is a major advantage in an alternating current: the voltage can be raised with ease to a higher or lower voltage. This means that electrical energy can be sent over huge distances with high voltage. With that, the voltage can be reduced to a securer level for its daily use.

Did you know: when Thomas Edison opened a generating plant in New York, he used direct current. New York had an area of 2.6 square kilometers served by generators. 

EM 13: I can explain why the Earth behaves like a magnet and the consequences of it.

The earth was found to be a magnet in the late 1500s, when an English physician called Sir William Gilbert became interested in compasses. He affirmed that a compass always points in the same direction. He guessed that because he believed that the Earth acted like an enormous magnet. He was right. 


Just like a normal magnet, the Earth has a magnetic field surrounding it and two magnetic poles. Within the earth as a magnet, there is a term called magnetic declination, which is the angle between north and geographic north, which is where the needle in the compass points.

EM 14: I can explain the importance of grounding wires and using fuses/circuit breakers.

A grounding wire is a common use in household electric circuits. A low enough resistance is guaranteed once the path goes through a fuse in case of fault of energy. A fuse/circuit breaker is a material wrapped around with a piece of metal string. A grounding wire also protects against electrical shock. When too much voltage is used at the same source, a fuse comes into play. The excess of energy wasted goes to the fuse, which causes the metal string to melt. The disadvantage of fuse is that it needs to be replaced once the metal string is wasted and totally melted. It can be easily replaced (no hard work).

EM15: I can explain how an electromagnet works and cite applications for them.

An electromagnet is a solenoid with a ferromagnetic core. In an electromagnet, magnetic field is produced by both the current in the wire and the core that is magnetized. Electromagnets can be turned on and off and they are extremely powerful magnets. Maybe you won't notice, but you use an electromagnet every day. Every time you hit the doorbell you are activating and electromagnet. Because such materials as tapes of all kinds, computer hard drives, credit cards, and even doorbells use electromagnets.
Observe the animation for a better understanding:

EM16: I can explain how a simple motor works (parts and function).

Parts of the motor:

Battery: The battery is a material that starts the current, which flows through the brushes.

Armature: the armature will interact with the permanent magnet and become an electromagnet. It is the ferromagnetic material of the motor.

Commutator: The function of the commutator is to stop the current as it spins together with the armature.

The steps of the how a simple motor works follows:

1.) There is not a magnetic field to interact with the permanent magnet around the armature. The domains in the armature are not aligned for that reason.

2.) The battery is the material that starts the current through the brushes, armature, and the commutator, returning through the other side of the battery.

3.) A magnetic field is then created around the armature as the current makes the domains align.

4.) Now, both magnetic fields align (from the armature and from the permanent magnet). But when this happens, the current stops because the circuit gets opened. This happens because a space is created in the commutator.

5.) Because it is stopped, the armature will continue to rotate, and a bit later, the brushes will have contact with the commutator again, by closing the circuit and making the same process restart.

EM17: I can describe how a generator and a transformer work.

Generators have the exact opposite job of a motor. A generator uses motion to create and electric current. An AC (Alternating Current) is induced by a moving magnet. The AC (Alternating Current) and the DC (Direct Current) are almost the same. The only difference is that the AC Generator has a slip ring instead of a commutator. The generator works in a simple way: When the crank is turned, the armature spins in the magnetic field; one side of the armature moves up while the other moves down (this movement created a current). But this current is happening in opposite direction in the two sides of the armature. Once the armature is half turned, each side reverses their direction as the current changes direction as well. The final result of all this will be an alternating current.

EM18: I can explain the importance of transformers to power grids.

At home, office, etc. there can't be a very high voltage because an explosion could occur or the appliances would be severely damaged. Therefore, you don't lose too much energy when it is in form of heat (job of transformer). This is why transformers are important to power grids.

EM19: I can explain methods of power production and distribution.

The methods of power production and distribution were worked in our science class with a partner and it follows:

. Nuclear Energy: Chemical --> Thermal --> Mechanical --> Electrical

. Solar Energy: Electromagnetic --> Electrical

. Geothermal Energy: Thermal --> Mechanical --> Electrical

. Hydroelectric Energy: Mechanical --> Electrical

. Wind Energy: Mechanical --> Electrical ::: (oposite from hydroelectric energy).

. Bio Mass: Chemical --> Thermal --> Mechanical --> Electrical

. Fossil Fuels: Chemical --> Electrical

EM20: I can describe the differences of 110v/220v and main advantages and disadvantages of each.

There is a bigger advantage on 110v over 220v. Observe:

.110:

Advantages:

. Less dangerous if a problem occurs.

. Most materials/appliances are 110v.

Disadvantages:

. More energy is lost in form of heat.

.220:

Advantages:

.Lose less energy in form of heat. (opposite from the disadvantage in 110v).

Disadvantages:

. More dangerous if a problem occurs.

EM21: I can describe the advantages and disadvantages of electrical energy.

There are much more advantages in electrical energy than disdvantages. Observe:

Advantages:

. Easy to be transported

. Easy to be converted to another form of energy.

. Easy to be controlled.

Disadvantages:

. May come from a polluting source.

*A good website to study all of these concepts in a simulation follows:
http://phet.colorado.edu/en/simulation/faraday