A charged particle moving parallel to a magnetic field experiences a force of

  • A. maximum magnitude
  • B. zero
  • C. half the maximum
  • D. qvB

Explanation

The magnetic force is qvB sin theta, and sin 0 is zero, so a charge travelling along the field lines feels nothing at all. The force is maximum when the motion is perpendicular to the field, and it is then qvB. This angular dependence is why charged particles from the Sun spiral in along the Earth's field lines near the poles and produce aurorae.

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