Fields of Everything
We recently studied magnetic fields in our lab. We mapped the field of a bar magnet and a coil. Then we graphed the intensity of a bar magnet versus distance. It was a simple lab but it has some far reaching ideas that we really should deal with.
First of all, just what is a field? We have studied three types of field thus far this year. Gravitational fields are measured in acceleration, m/s^2 or N/kg. All masses have a gravitational field that affects their surroundings by attracted other masses toward themselves. Electric fields are a little more difficult to comprehend. They are measured in N/C and represent the effect on the surroundings of a charged particle. We studied this in a previous lab when we measured the voltage in a pan of water that had two parallel conducting plates in it. Now we come to magnetic fields and we gathered some data that hopefully shed some new light light on an old concept.
Second, what is the mathematical desription of a field? Think about it. Gravitational field...N/kg...electric field...N/C...what would you predict would be the units of magnetic field intensity? Defend your answer. What can you infer about magnetic fields from what we have discussed about electric fields and gravitational fields?
Finally, what about the relationship with distance? For gravitation we have Newton's Law of Universal Gravitation. For electric fields and charged particles we have Coulomb's law. What does your data tell you about the intensity of a magnetic source as you get further away from it? What regression did you do on your data and what does it tell you?
Write up this lab by responding to this blog. Respond to the questions that are proposed in bold italics above. As always be illustrative and factual and make your response a minimum of three ample paragraphs. Site at least one source that you used to help prepare your response and it cannot be you textbook. As always, when you are done respond to one of your colleagues.
posted by edlegare @ 5:57 PM
4 Comments
4 Comments:
A field is a space that has a general dirction and attraction to surrounding matter, or internal matter. A field is like a river. It flows in a general direction and then when a person jumps in on a raft, the raft is taken by the current along the directional pull.
The mathematical deffinition of a field is a Newton per Tesla (N/T).
If gravity is Newtons per Kilogram, and electricity was Newtons pers Coulomb, when we were studying electical fields, the Coulomb was a new unit, and since the Tesla is the new unit for magnetism, it only makes sence to say it is Newton's per Tesla.
Well, with gravity the farther away any two objects are, the less of a force between them. With Electrical fields, we can look at a simple demonstration from class. A vandegraph generator creates a field of elecrons around the metal ball at the top. If you place a hair close enough to the generator you can get a spark. Notice i said close enough. What i am implying is that the farther the distance between two oppositely charged perticles the more work that has to be done in order for that spark to happen. And more work means a bigger field. With magnetic fields, the idea is the same. When two magnets are placed near eachother, the opposite ends attract, just like the positive and negative charged particles do. However, if the seperate magnetic fields of the magnets are not close enough to collide, then as far as magnetics go the attraction between the two magnets won't exist.
I would also like to make another point about the fields and attraction. Although, two magnets might not be close enough to attract, thanks to Newton we can safely say that there is a gravitational attraction between the two magnets. Not to mention there is also the gravitaional pull of ther earth. Say a spherical magnet is suspended in the air. And a small spherical piece of iron is dropped so that it will fall along side of the magnet, and into the outside of the magnetic field. Gravity would be pulling the piece of iron down, but the magnet would also pull the iron sphere towards it. Potentially the iron would orbit the magnet, causing a replica of the earth and the moon.
_ _ _ _ _ _ _
_B_E_E_K_E_R_
what exactly is a field?...it is a uniform force of one kind generated between a source and an endpoint. A magnetic field is one between the north and south poles of a material that produces magnetism. It makes sense to me that all fields are made up of the same basic energy because they can all attract another object. Magnetism, which is closely related to electricity, is caused by the movement of charged paritcles and is thus created by electric current in a wire and can inversely induce a current in a wire moving through it.
Mathematically...i would predict that the units for the field intensity would be a Newton per standard unit of magnetic flux lines...so N/Weber. However one Tesla is a Wb/m^2...i dont see any connection between the two but thats how I think it would be. Several sources which have already been posted state that the standard unit is an Ampere per meter, which is simply the strength of the field at a certain distance at a point rather than the field as a whole.
Using the graph from the lab and an exponential regression, I realized that the strength of the magnetic field varies inversely with the distance squared just like both electric fields and gravitational fields.
To add to the confusion of everyone...look up the standard unit of magnetic flux density: a Weber. the Weber is used in the argument that everyone is giving that a Tesla=A/m. this is not true. using
1 T = 1 Wb•m-2 = 1 kg•s–2•A–1= 1N•A–1•m-1 = 1 kg•s–1•C–1
one must realize what the leters Wb mean to understand. Also, nowhere within that equation does it state that 1 T = 1 A/m ...look it over carefully.
I agree with beeker's definition of a field. when an object that is subject to the field type is within the field it will pull it along the flow of the field.
in my original post (thanks guino) take out the word "uniform" in my second sentence...it shouldnt be there...
Post a Comment
Subscribe to Post Comments [Atom]
<< Home