A student gradually rotates the velocity vector of a charged particle while keeping…
PHYSICS · Multi-part · AP · Physics 2: Algebra-based · Magnetism and Electromagnetism · Magnetism and Electromagnetism
Problem
A student gradually rotates the velocity vector of a charged particle while keeping its speed and the external magnetic field magnitude constant. The angle θ between the velocity vector and the magnetic field is increased from 0∘ to 180∘.
(a) On axes you provide, sketch a qualitative graph of the magnitude of the magnetic force on the particle versus the angle θ for 0∘≤θ≤180∘. Label the key numerical values of θ at which the graph has zeros or extrema.
(b) Suppose the particle’s speed is doubled while the same range of angles is swept through. On the same set of axes, sketch a second curve representing the new force–angle relationship, and briefly describe how the two curves differ.
(c) Explain, in words, the physical reasons for the features you identified at θ=0∘, 90∘, and 180∘. Your explanation should reference the interaction between the particle’s motion and the magnetic field.