Magnetic Field of a Loop: Difference between revisions
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If the distance from the center of the loop is much greater than the radius of the loop, an approximation can be made. The formula can be simplified to | If the distance from the center of the loop is much greater than the radius of the loop, an approximation can be made. The formula can be simplified to | ||
<math>\vec B=\frac{\mu_0}{4 \pi} \frac{2I \pi R^2}{z^3} \text{ ,where z | <math>\vec B=\frac{\mu_0}{4 \pi} \frac{2I \pi R^2}{z^3} \text{ ,where z is much greater than R} </math> | ||
===Direction of Magnetic Field on z-axis=== | ===Direction of Magnetic Field on z-axis=== |
Revision as of 13:57, 29 November 2015
Claimed by Jeffrey Mullavey
Creation of a Magnetic Loop
Like other magnetic field patterns, A magnetic field can be created through motion of charge through a loop. Ideal loops are considered to be circular. Thus, the conventional current is directed clockwise or counterclockwise through the loop.
Calculation of Magnetic Field
The magnetic field created by a loop is easiest to calculate on axis. This means drawing a line though the center of the loop perpendicular to the circumference. This axis is commonly referred to as the "z-axis." The magnetic field is calculated by integrating across the bounds of the loop (0 to 2 pi), but can also be approximated with great accuracy using a derived formula.
Magnitude of Magnetic Field on z-axis
When calculating the magnetic field at a point on the z-axis, one can use the following formula:
[math]\displaystyle{ \vec B=\frac{\mu_0}{4 \pi} \frac{2I \pi R^2}{(z^2 + R^2)^1.5} \text{ ,where R is the radius of the circular loop, and z is the distance from the center of the loop} }[/math]
This allows for the calculation of the magnitude in units of Teslas.
If the distance from the center of the loop is much greater than the radius of the loop, an approximation can be made. The formula can be simplified to
[math]\displaystyle{ \vec B=\frac{\mu_0}{4 \pi} \frac{2I \pi R^2}{z^3} \text{ ,where z is much greater than R} }[/math]
Direction of Magnetic Field on z-axis
The right hand rule can be used to find the direction of the magnetic field at a given point. Putting your right fingers in the direction of the conventional current, and curling them over the vector r will allow your thumb to point in the direction of the magnetic field. For example, a conventional current, I, running counterclockwise would produce a field pointing out of the page on the z-axis. This rule holds regardless of where the observational location is on the center axis.
References
Matter and Interactions Vol. II