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Motional EMF

  • When a conducting rod of length L moves with speed v in a magnetic field B that is perpendicular to both the rod and the direction of motion, an emf is induced across the rod. This emf, known as motional emf, is given by BLv.
  • If a rod, of length L, rotates with angular velocity w about a pivot at one end of the rod, and if a magnetic field exists in space, perpendicular to plane of rotation, an emf will be induced in the rod; it is given by (1/2)wBL^2.
  • Examples are provided in the lecture that show how to calculate the force that an external agent must exert in order to pull a rod on rails at constant speed in the presence of a magnetic field, and in the absence of this force, how the speed of the rod decreases with time.

Motional EMF

Lecture Slides are screen-captured images of important points in the lecture. Students can download and print out these lecture slide images to do practice problems as well as take notes while watching the lecture.

AP Physics C: Electricity and Magnetism