The current $I$ in the wire is varied while the angle $\theta$ remains constant. On Fig. 6.2, sketch a graph to show how the force $F$ on the wire varies with current $I$.
The angle $\theta$ between the wire and the magnetic field is now varied, while the current $I$ is kept constant. On Fig. 6.3, sketch a graph to show how the force $F$ on the wire varies with angle $\theta$.
A uniform magnetic field acts at right-angles to the rectangular surface PQRS of a slice of conducting material, as shown in Fig. 6.4. Electrons moving towards side SR enter the slice of conducting material. The electrons enter the slice at right-angles to side SR.
Explain why, at first, the electrons do not move in straight lines across the slice from side SR to side PQ.
Explain whether the electrons tend to move towards side PS or QR.