Last Moment: ¡ Search for North Pole South Pole!
(magnetite).
Teaching unit: Magnetism
Teacher: Carlos Trapani
Alumnae: Agostina Bolasini and Eliana Millan
2nd quarter 2010
Last Moment: ¡ Search North Pole the South Pole!
(magnetite).
Purposes:
• students propose experimental activities that include questioning, anticipation of results, discussion of the variables involved, instrumental manipulation, observation, use of records and discussion of results.
• Select topics that include teaching situations where students must be made increasingly accurate observations and focused.
Grounds: The way it is developed, this work highlights the interest to find that children are partakers of their own learning, ie trained to use the materials and tools to address the issue in question.
The use of elements in the daily life nears its Once the relationship of the content being taught in school with their context, so that you can make sense of each phenomenon are presented.
believe that in this case the collective work is an indispensable tool both to find and compare different views as well as to carry out the experiments.
Contents:
• Exploring magnets and their effects on different materials.
- Identification of the poles of magnet. Attraction and repulsion between poles of magnets.
• Establishment of similarities and differences between the effects of the electrification and the magnetization.
• Finding information on the operation and usefulness of the compass.
Objective: To encourage students to observe, for example, the diversity of shapes, sizes and intensities that have magnets, and to warn that the action of magnets on objects manifest at a distance and through different materials. And also sought to observe its functionality to see them reflected in everyday items.
offer group and individual work.
Individual work: graphic narrative register.
Group work: achievements of experiences.
Teacher Interventions to expand the vocabulary.
Sharing, what discover? What else would you find?
request them to kids, a picture / diagram to express their ideas.
1 - Activities: exploration of the magnets and materials.
2 - Materializing the magnetic field of a magnet.
First phase: what is a magnet?
interaction of the magnets, with objects of different materials.
Test magnets in coins, keys, woods and the kids, then an explanation as the currency does not stick because it is old, the wooden rule is that the magnet does not stay, it is dirty and then the magnet will not stay, can determine where the magnets are attracted.
be clear that is not the type of object that determines whether or not to be attracted by the magnet, but the material is done, and that only the ferromagnetic are attracted by magnets.
Activity 1
Objective: The kids know and understand the concept of magnet and its functionality through the experience.
Resources:
• a bag with different objects (made of a single material, plastic, paper, metal, iron, steel, copper, aluminum etc. .)
• a magnet.
• a role as a registration form to record predictions, observations and conclusions.
Procedure. (Working Mode)
- The boys removed objects that are in the bag. Our trigger questions may be: "What do you think will be attracted by the magnet? Before testing what happens to the magnet to record their predictions on the card, placing the names of every object in the appropriate column.
- In a second instance: "What criteria used to classify objects? Can you state a rule about what will be attracted by the magnet? Write it briefly on the record. "
- Then the kids use the magnet to verify their predictions, testing them one by one all the objects. "As they do, complete the form with the results."
- wonder In closing, to verify their predictions, "When is fulfilled what they had expected? Why would not you? Is it complied with the rules or think they should change it? If so, how would set out a new rule? Write your findings on the record. "
It will conclude that things will be drawn must be metal.
second phase. How strong is a magnet?
Activity 2.
Objective: To enhance and expand your knowledge on the question of the force with a magnet that attracts a body varies with the distance between the body and the magnet, magnets will be shown several different and wonder how the would order, from highest to lowest, based on the force they can exert on an object. How can monitor and even measure which of the magnet is stronger?
Measure the minimum distance to bring a clip can not be attracted.
Resources:
• 2 or 3 different magnets
• Clips
• grid sheet.
Procedure. (Working Mode)
1. place the magnet on the grid sheet. Place the clip in another place on the sheet, away from the magnet.
2. slowly bring the magnet to the clip, record the distance (squares) to which the clip starts to be attracted.
3. repeated with another magnet.
Activity 3.
Count how many paper clips can be hung "chain" of a magnet.
Resources:
• 2 or 3 different magnets.
• Clips
Procedure: (work mode)
- build a string with two clips, one with three clips, etc.
- test which of them remain attached when suspended magnet.
- register which is the largest chain, supported by the magnet.
- repeat with a magnet different.
Third phase: Can you make a magnet?
Activity 4. Making Magnets.
Objective: boys are expected to be able to apply what they learned earlier for easier construction of a magnet.
We will make the boys rub a piece of iron and then verify that it behaves like a magnet. The object can be rubbed a nail or needle. The procedure magnetize a needle will be useful later to build a compass and watch focuses on the Earth's magnetic field.
Resources:
a magnet •
• a piece of iron (can also be a pin or needle)
• clip
Procedure (working mode)
- Tocá the clip with a piece of iron. What happens?
- now takes the piece of iron with one hand. With the other, rub the magnet on the piece of iron.
- repeated the second step at least twenty times, always rubbing in the same direction and the length of the piece of iron.
- Tocá clip again with the piece of iron. What happens?
Fourth phase: Where is stronger magnet?
Floating Magnet Activity 5.
Objective: That guys understand that the force exerted by the magnet is not the same over its entire surface, but is particularly concentrated in some areas which are its poles .
Resources:
• A needle (can also be a paper clip)
• a small flat object, floating on the water (like a cork, or a flat piece of styrofoam.)
• container 20 to 30 centimeters wide, with 2 or 3 centimeters cubic .
Procedure (working mode)
- needle becomes a magnet, following the steps of the activity "making magnets."
- needle fixed to polystyrene or cork and place them in water so they float.
- wait a moment and see what happens with the needle?
- with the container in your hands, rotate in different directions or walk forwards or backwards. Observe what happens to the needle.
- about a magnet to the needle. What happens?
In another activity, may indicate whether the poles of magnets are north or south pole by reference to a compass and built for them.
rating: boys will be evaluated during development, this work. As well, we will seek to be able to apply what they learned in the last activity and, therefore, practically and theoretically to justify the experiment carried out.
conceptual overview
Magnetism and electricity
Review: Magnetism and Electricity
· What is a magnet?
· What is magnetism?
· How magnetism produce electricity?
Magnetism is one of the most attractive and mysterious phenomena known since antiquity, originally manifested through the attraction of certain stones called magnets on some specific materials such as iron , nickel and cobalt. It is now known that all matter has magnetic properties under certain conditions and there are different types of magnetism and magnetic variables that characterize it. This refers to the most basic manifestations of the magnets.
| What is a magnet? Stone of Hercules was one of the names that the Greeks gave this mysterious stone. Magnesia Stone was another, due to the abundance of this mineral in this region of Asia Minor, for Latinos was the name used magnes where magnetism comes from the word, a word used today to designate the property of the magnet to attract other materials and all knowledge about it. The stones are natural magnets of iron oxide called magnetite (Fe 3 O 4 ), Who purchased the property to attract some elements such as iron, cobalt, nickel, gadolinium, dysprosium and alloys of these elements. |
| |
These materials are given the name of ferromagnetic and thus differ from other materials with weaker magnetic properties such as diamagnetic and paramagnetic.
was William Gilbert who brought the knowledge that his time had on the magnetic phenomena, adding to the themselves the valuable wealth of his own experiments, determining the most interesting features of the magnets.
| Characteristics of Magnets. is oriented in a specific address space when properly suspended. If any magnet hung in space by a thread shows that acquires a special orientation: part of the magnet is oriented approximately toward true north and the other is oriented toward the south. The side that points north is called the north pole of the magnet and the side that points south is called South Pole. This feature gave rise to the compass, an instrument built with a small magnetic needle that can rotate around a rotation axis passing through its geometric center. |  |
For example: between magnets can be seen that the poles of the same name poles repel and different name will attract , as shown in the following animation.
| But when a magnet is brought close to a piece of iron or another ferromagnetic material shows that there is always attraction between them and she is strong when the ferromagnetic material approaches the poles. | |
 b) They have a buffer zone where the attractive properties on ferromagnetic materials are weakened, this is the neutral zone of the magnet. As can be seen in the figure below, in this area has no nails. c) If they break into two parts we get two new magnets. So far it has been possible to separate the poles of a magnet and isolate them, the magnets are always bipolar and magnetism for this reason, it talks of magnetic dipoles. | |
| d) lose property to attract when heated to certain temperatures. There is a temperature where the magnetism disappears. The iron nail is attracted to the magnet in the figure, it loses its magnetization when heated with the burner at 770 ° C. | |
 | magnetic field magnets Gilbert realized that the magnetism of the magnets did not reside in the magnet only, but also in the space surrounding the magnet, thereby creating the basis of the concept of magnetic field of a magnet. This statement is displayed if you place small chips iron on the side of a sheet of paper and the reverse side is placed a magnet, depending on the shape of the magnet will be observed that the chips are aligned in space, according to Michael Faraday imaginary lines called lines of force. |
| terrestrial magnetism. Earth, William Gilbert wondered, would it not be a huge magnet? Gilbert took steps to understand why a compass is oriented North-South direction. He thought that the earth must necessarily behave like a giant magnet whose magnetic north pole is attracted to the pole compass south and vice versa, the south magnetic pole of Earth must attract the north pole of the compass. |  |
| To test this hypothesis, the tireless experimenter builds a spherical magnet, its famous microg (Earth lowercase), and closer to its magnet , a small magnetic needle moving around its center of gravity, shows that it behaves like an inclination compass (compass that measures the angle of the magnetic field Earth with respect to the horizontal) suspended in a meridian plane of the Earth. | |
 | Gilbert believed that the magnetic poles coincide with the geographic globe, however, the compass always points to no geographic north, this had been aware the Chinese in the twelfth century BC and is now known that the North Pole is in a different magnetic pole (magnetic south pole) to which a compass points. The North Pole is in Greenland and the magnetic pole is in the Queen Elizabeth Islands. |
| said Paul Hewitt, who knows for sure why Earth is a magnet. The Earth's magnetic field configuration is like a powerful bar magnet placed near the center of the planet. But Earth is not a piece of magnetized iron as the bar magnet. It is too hot for individual atoms remain aligned. currents flowing in the Earth's fiery region, under the bark, are a better explanation of Earth's magnetic field. | |
| Most students of earth science believe that the Earth's magnetic field due to the motion of charged particles that rotate inside the planet. Given the large size of the Earth, the speed of charged particles should be less than a millimeter per second to produce the field. Another possible explanation for Earth's magnetic field are the convection currents that occur due to heat from the core (see figure). |  |
| The Earth's heat is due to nuclear energy that is released in the process of radioactive decay. Perhaps the Earth's magnetic field is derived from a combination of convection currents to the effects of Earth's rotation. But more research is necessary to establish a more firm. Whatever its cause, the Earth's magnetic field is not stable, but is shifted in the course of geological time. The evidence of this fact comes from the analysis the magnetic properties of the rock strata. Iron atoms in the molten state tend to align themselves with Earth's magnetic field. When iron solidifies the direction of the magnetic field is recorded in the orientation of the magnetic domains of the rocks. We can measure the slight magnetism resulting by sensitive instruments. Thus, by measuring the magnetism of different rock samples from strata that have formed at different times can produce maps of the Earth's magnetic field in different eras. The traces left in rocks show that there have been times when the Earth's magnetic field has been reduced to zero and then reversed. During the last 5 million years there have been over twenty investment. The most recent dating back 700 000 years. Other past investments occurred and makes 870 000 950 000 years. Studies of ocean-floor sediments indicate that the field has been virtually dormant for some 10 000 or 20 000 years ago little more than 1 million years. This is the time when modern humans emerged. We can not predict when the next investment because the sequence is not regular. But some recent measurements show a reduction of 5% in the intensity of Earth's magnetic field in the last 100 years. If the change is maintained is quite possible that the field re-invested in less than 2000 years. | |
Electricity and Magnetism: What is electromagnetic induction?
The electrical current can create magnetic effects. If a variable electrical current passes through a cable, a compass that is near the cable will be diverted. In other words, a variable electric current (moving electric charges accelerated) can produce a magnetic field. This was the first link was discovered between electricity and magnetism.
 |
| Hans Christian Oersted (1777-1851) |
One day, while poking at a large desk full of equipment in front of a class, noted that whenever a battery connected to a circuit, the compass needle moved nearby. This accident was the basis of what may have been one of the most important discoveries ever made practical.
The great advantage of an electro-magnet is that it can be connected and disconnected. An electro-magnet is a round (or rounds) of thread through the which an electric current flows. The electricity produces a magnetic field: the more laps you have the thread (and stronger current), the stronger the field.
Thus, the turns of wire behave exactly like an ordinary magnet and metal parts can boost as any of them. Force the magnet can be adjusted by regulating the amount of current passing through the wire .
For example, scrap yards that we often are used to lift car magnets. When current passes through the magnet, car magnet is attracted and, usually suspended from a crane can lift it. When the operator wishes to drop the car off the current. As soon as the current stops, the turns of wire stop acting like a magnet and the car is no longer attracted to him. The force of gravity (which has always been there) took back the reins and the car falls.
magnetic fields can cause electrical effects. This is another connection between electricity and magnetism. If we move a magnet around a few laps of thread, or if we turn this around near a magnet, by turns of wire an electric current flow, even when no voltage source.
This phenomenon, known as "electromagnetic induction" was discovered by Michael Faraday (1791-1867) and made possible our modern society driven by electricity.
there a connection between the static that clings to our clothes and a magnet that holds a note on the door of our refrigerator as there is in all electrical and magnetic phenomena. In fact, the discovery of this connection marks one of the highlights of physics of nineteenth century.
What we know today is that electricity and magnetism are simply different aspects of the same fundamental force, which we call the electromagnetic force.
Videos interesting
http://www.youtube.com/watch?v = Dbo8ovHRZFU
http://www.youtube.com/watch?v=zOdboRYf1hM&feature=related
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