Magnetic Field This pre-lab examines the magnetic fields. We will examine the fo

Question

Magnetic Field
This pre-lab examines the magnetic fields. We will examine the following two main areas.

1. The magnetic field produced by a straight current carrying wire.
2. The resultant magnetic field due to the earth's magnetic field and a current carrying wire.

Magnetic fields are produced by moving charges or electric currents. For example, if you pass a direct current through a wire you can detect the presence of magnetic fields around the wire by using some iron filings or a small compass. In bar magnets there exists magnetic dipoles at the atomic level that are responsible for the presence of the magnetic field. The earth's magnetic fields are the result of the earth molten core which is under constant rotation. The rotation and iron in the molten core acts like a giant current loop. The magnetic south pole of the earth's magnetic fields is near the geographic north pole.
Note: There are two exercises for this pre-lab. As you complete one exercise or have exhausted all your tries, the next exercise will be displayed since it may depend on the results of the earlier exercise(s). In addition, this significantly reduces the time to process each submission. When you have exhausted all your tries, the computer's answer will be displayed.
Exercise 1 - Magnetic Field Due to a Straight Current Carrying Wire
For a long straight wire carrying a current I, the magnitude of the magnetic field, B produced at a perpendicular distance, r from a wire is given by
B=2r0I
where 0=4107NA2 or (ATm) is the magnetic permeability of free space and is a constant. The amount of electric current, I is measured in Amperes (A) and r is measured in m. Thus the circle formed by the distance r from the wire has magnetic field of the same magnitude. However, the direction of the magnetic field at a point on the circle is the tangent at that point. Since there are two possible directions for the tangent, the direction, by convention, is determined by the right hand rule. Learn more using java applet simulations. Study the applet carefully and answer the following questions.

The next step is to calculate the strength of the magnetic field at the various points. Since they are all the same distance from the current, the magnitude of the magnetic field is the same for all the points.

What is the magnetic field at E? The unit for magnetic field is T (Tesla).

Explanation / Answer

a) The magnetic field at A is along West direction due to the right hand rule,
b) The magnetic field at E is along East direction due to the right hand rule,
c) The magnetic field at C is along NorthEast direction,
d) The magnetic field at D is along SouthEast direction.

Magnetic field due to a long straight wire is known, the other part is just calculation, at all!

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