12.2 Magnetism and Moving Charges

Describe the magnetic field produced by moving charged objects.

• A single moving charged object produces a magnetic field.
  • i. The magnetic field at a particular point produced by a moving charged object depends on the object’s velocity and the distance between the point and the object.
  • ii. At a point in space, the direction of the magnetic field produced by a moving charged object is perpendicular to both the velocity of the object and the position vector from the object to that point in space and can be determined using the right-hand rule.
  • iii. The magnitude of the magnetic field is a maximum when the velocity vector and the position vector from the object to that point in space are perpendicular.

Describe the force exerted on moving charged objects by a magnetic field.

• A magnetic field will exert a force on a charged object moving within that field, with magnitude and direction that depend on the cross-product of the charge’s velocity and the magnetic field. Relevant equation: Fq vBB    ()=×
• In a region containing both a magnetic field and an electric field, a moving charged object will experience independent forces from each field.
• The Hall effect describes the potential difference created in a conductor by an external magnetic field that has a component perpendicular to the direction of charges moving in the conductor.