Hall effect
I am having trouble understanding what the Hall effect is. Please help with what it actually is conceptually. What causes it and what are its effects?
Answer
The effect of a magnetic field on a charged particle is to apply a force:
F = q v B sin θ
where θ is the angle between the velocity and the magnetic field. You know that in a conductive wire, electrons can flow as current. If there is an external magnetic field perpendicular to the wire (θ = 90 degrees), the electrons will experience a force that sends them towards one side of the wire. Notice that the force law contains the charge q -- in other words, negative charges will experience a force opposite that of positive charges. The result is that negative charge will build up on one side of the wire, and positive charge on the other.
This division of charge creates essentially a capacitor, which you know creates an electric field and thus a voltage difference from one side of the wire to the other. The result is that by measuring the Hall effect we can measure the density of charge carriers, determine whether positive or negative charges are flowing, and measure the strength of magnetic fields.
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The effect of a magnetic field on a charged particle is to apply a force:
F = q v B sin θ
where θ is the angle between the velocity and the magnetic field. You know that in a conductive wire, electrons can flow as current. If there is an external magnetic field perpendicular to the wire (θ = 90 degrees), the electrons will experience a force that sends them towards one side of the wire. Notice that the force law contains the charge q -- in other words, negative charges will experience a force opposite that of positive charges. The result is that negative charge will build up on one side of the wire, and positive charge on the other.
This division of charge creates essentially a capacitor, which you know creates an electric field and thus a voltage difference from one side of the wire to the other. The result is that by measuring the Hall effect we can measure the density of charge carriers, determine whether positive or negative charges are flowing, and measure the strength of magnetic fields.