experiments >> the coupled pendula experiment
Magnetic field of a paired coil in the Helmholtz arrangement
Some related information and facts:
Each of the similar Helmholtz coils is cantilevered off a plastic foot. The sockets of the coil winding are cast into the plastic foot of the coil; and the connecting leads can be used to connect the coils in parallel or series as required. Cantilevering the coils from the base allows the number of turns to be counted. The fact that the turns of the individual layers are slightly offset relative to one another must be allowed for when counting.
Two stainless-steel round rods are provided to specify the distance between the coils at 200 mm, so that their axial spacing is equal to the average coil radius. The spacers can be removed after un-screwing knurled screws; allowing the coils to be used individually.
Related subjects to learn about:
› Maxwell's equations
› Wire loop
› Flat coils
› Biot-Savart's law
› Hall effect
Relevant information:
Hermann Ludwig Ferdinand Helmholtz German scientist and philosopher has made fundamental contributions to physiology, optics, electrodynamics, mathematics, and meteorology. He is best known for his statement of the law of the conservation of energy.
The physicist, James Clerk Maxwell in the 19th century based his description of electromagnetic fields on four equations, which express experimental laws. The statements of these four equations are, respectively:
› electric field diverges from electric charge, an expression of the Coulomb force,
› there are no isolated magnetic poles, but the Coulomb force acts between the poles of a magnet,
› electric fields are produced by changing magnetic fields, an expression of Faraday's law of induction, and
› circulating magnetic fields are produced by changing electric fields and by electric currents,
Maxwell's extension of Ampère's law (q.v.) to include the interaction of changing fields.
Hall effect: Development of a transverse electric field in a solid material when it carries an electric current and is placed in a magnetic field that is perpendicular to the current. The U.S. physicist Edwin Herbert Hall discovered this phenomenon in 1879. The electric field, or Hall field, is a result of the force that the magnetic field exerts on the moving positive or negative particles that constitute the electric current. Whether the current is a movement of positive particles and negative particles in the opposite direction, or a mixture of the two, a perpendicular magnetic field displaces the moving electric charges in the same direction sideways at right angles to both the magnetic field and the direction of current flow.
The accumulation of charge on one side of the conductor leaves the other side oppositely charged and produces a difference of potential. An appropriate meter may detect this difference as a positive or negative voltage. The sign of this Hall voltage determines whether positive or negative charges are carrying the current.
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experiments >> the coupled pendula experiment