A2L Item 228

Goal: Reason regarding electrodynamics

Source: 283-635 Path of a charge in E&B fields.

charge has an initial velocity parallel to the y-axis in E and B fields.
Both fields point along the x axis. Which of the following statements
regarding the charge’s motion are correct?

  1. The charge will travel along a straight-line path.
  2. The charge’s speed will change as it travels.
  3. The charge will travel in a helical path.
  4. The charge will travel in a helical path of increasing pitch.
  5. The charge will travel in a circle in the x-y plane.
  6. 1 and 2 only
  7. 2 and 4 only
  8. None of the above



(7) A common response is #4 because they forget that increasing pitch
implies that the speed changes.