Magnetic Forces and Fields (Physics)

Recall cards on magnetic forces and fields. Magnets and Earth's field: the two poles, attraction and repulsion, the absence of magnetic monopoles, Earth as a bar magnet, compass behavior, field reversals, and the historical discoveries of Oersted, Ampere, Arago, and Faraday. The magnetic field: its definition through the force on a moving charge, F = qv x B, F = qvB sin(theta), the tesla and gauss, the right-hand rule, and field lines. Motion of a charged particle: circular and helical paths, why the magnetic force does no work, r = mv/(qB), the period T = 2 pi m/(qB), pitch, magnetic bottles, and the Van Allen belts. Force on a current-carrying conductor: RHR-2, F = IL x B, F = BIL sin(theta), and the zero net force on a closed loop. Force and torque on a current loop: the magnetic dipole moment mu = NIA, tau = mu x B, tau = IAB sin(theta), the potential energy U = -mu . B, electric motors, and the commutator. The Hall effect: Hall's experiment, the Hall voltage, the force balance, drift speed, velocity selectors, and identifying charge carriers. Applications: the mass spectrometer and the cyclotron.