An electron is travelling in a vacuum at a speed of 3.4 × 10⁷ ms⁻¹. The electron enters a region of uniform magnetic field of flux density 3.2 mT, as illustrated in Fig. 8.1. The initial direction of the electron is at an angle of 30° to the direction of the magnetic field.

1. (a)(i)When the electron enters the magnetic field, the component of its velocity v_N normal to the direction of the magnetic field causes the electron to begin to follow a circular path. Calculate: v_N v_N = ............................................................ ms⁻¹[1]
2. (a)(ii)the radius of this circular path. radius = ............................................................ m[3]
3. (b)State the magnitude of the force, if any, on the electron in the magnetic field due to the component of its velocity along the direction of the field.[1]
4. (c)Use information from (a) and (b) to describe the resultant path of the electron in the magnetic field.[1]

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