IB Physics. Electron Moving in a Magnetic Field

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A tutorial sheet for the motion of a charge in a magnetic field is given below.

An electron enters a region of uniform magnetic field of flux density 1.2 × 10-3 T with an initial velocity of 3.0× 107 m s-1 at an angle of 30.0° to the magnetic field.

  1. Describe the path of the electron in the magnetic field.
  2. Find the time taken by the electron to make one complete revolution about the magnetic field lines.
  3. Find the cross sectional radius of the path of the electron.
  4. Find the work done by the magnetic field on the electron in 10 ms.
  5. Suppose that the magnetic field increases uniformly in time. Is the work done on the electron zero? Does the speed of the electron change?
  6. Suppose that the magnetic field is proportional to z and the electron is injected at 30.0° to the z axis. Is the work done on the electron zero?