Free AP Physics C lesson

Magnetic Fields & Lorentz Force

This AP Physics C: Electricity & Magnetism lesson is designed for AP Physics C self-study. It includes 4 video lessons, 6 practice questions, and an estimated completion time of 25 minutes.

Video lessons

  1. Magnetic Fields and Magnetic Force

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  2. The Motion of a Charged Particle in a Magnetic Field

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  3. The Mass Spectrometer

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  4. The Velocity Selector

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Practice covered

  1. The magnetic force on a moving charged particle is given by:
  2. A proton (q = 1.6 times 10^-19 C) moves at 2.0 times 10^6 m/s perpendicular to a 0.50 T magnetic field. Calculate the magnetic force in 10^-13 N.
  3. When a charged particle moves perpendicular to a uniform magnetic field, its path is:
  4. An electron (m = 9.1 times 10^-31 kg, q = -1.6 times 10^-19 C) moves at 5.0 times 10^6 m/s perpendicular to a 0.020 T field. Calculate the radius (in meters) of its circular path.
  5. A mass spectrometer separates ions based on their mass-to-charge ratio. After acceleration through voltage V, ions enter a magnetic field and follow circular paths. The radius depends on:
  6. A velocity selector uses crossed electric and magnetic fields. Particles with specific velocity pass straight through when:
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