Q8. a. Draw a diagram to illustrate how Fleming's left-hand rule can be used to check that if the current is flowing upwards and the field is directed out of the paper, then the force must act from left to right. (2) B b. If the force is 3.5 N, the current is 12.5 A, and the length of the conductor in the field is 9.5 cm, calculate the strength of the magnetic field. (3) c. If the length of conducting wire in the field is doubled, by what factor will the force increase or decrease? (1) d. Describe how these ideas apply to loudspeakers