How are the angles involved in deriving magnetic fields for a current loop?

In summary: If so, then the two angles are related by trigonometry; the angle labeled ##\theta## in the figure is what you get after factoring in the geometry of the problem.In summary, the conversation discusses deriving the magnetic field for a current carrying wire and a loop, with a specific focus on the angle of derivation. The formula used is ##\frac {ds * r} {r^2}## which becomes ##ds \sin \theta##, but the angle of derivation seems to vary depending on the source. The conversation also mentions the two angles involved in determining the magnetic field for a circular current loop at a point on its axis, specifically the azimuthal angle and the angle between the field element and the axis
  • #1
jisbon
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Homework Statement
Derive magnetic field at a point p away generated by current carrying loop and line.
Relevant Equations
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So I have managed to derive the magnetic field of a current carrying wire, however, I seem to have some enquiries on deriving the one for the loop. In the formula where ##\frac {ds * r} {r^2}##, I know that it will become ##ds sin \theta.## However compared to the theta in the wire, the theta that most derivations (I was searching for solutions) seems to be the angle at the point instead of the angle from the loop. Anyone can shine a light on this? Thanks
 
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  • #2
Bit hard to decipher your question without a drawing. Can I assume you are looking at the field in a point on axis ?
jisbon said:
most derivations
Utterly vague. Mention one or two explicitly.

Oh, and: ##\ dssin\theta\ ## looks ugly; at least use \sin : ##ds\sin\theta##
 
  • #3
If you are considering the magnetic field due to a circular current loop at some point ##z## on the axis of the loop, there are two angles involved, one is the azimuthal angle (normally labeled ##\phi##) that locates element ##d\vec s## on the current loop and the second angle (normally labeled ##\theta##) is the angle between the field element ##d\vec B## and either the ##z##-axis or one of the horizontal axes (see image below). Are these the angles you mean respectively by "theta in the wire" and "the angle at the point"?

Loop.png
 

1. How do the angles between the current loop and the magnetic field affect the strength of the magnetic field?

The strength of the magnetic field is directly proportional to the sine of the angle between the current loop and the magnetic field. This means that the greater the angle, the weaker the magnetic field will be.

2. What is the role of the right-hand rule in determining the direction of the magnetic field for a current loop?

The right-hand rule is used to determine the direction of the magnetic field for a current loop. When the thumb of the right hand points in the direction of the current, the fingers will curl in the direction of the magnetic field.

3. How is the magnetic field strength affected by the number of turns in a current loop?

The magnetic field strength is directly proportional to the number of turns in a current loop. This means that the more turns there are, the stronger the magnetic field will be.

4. Can the angle between the current loop and the magnetic field be greater than 90 degrees?

Yes, the angle between the current loop and the magnetic field can be greater than 90 degrees. In this case, the sine of the angle will be negative, resulting in a negative magnetic field strength.

5. How does the shape of the current loop affect the magnetic field produced?

The shape of the current loop can affect the magnetic field produced. A circular current loop will produce a uniform magnetic field, while a non-circular loop will produce a non-uniform field with varying strengths at different points.

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