A current flows in wire A in the direction shown on Fig. 7.1. On Fig. 7.1, draw four field lines in the plane PQRS to represent the magnetic field produced by the current in wire A.
A direct current is now sent through wire B in the same direction as the current in wire A. The current in wire B is greater than the current in wire A. On Fig. 7.1, draw an arrow in the plane PQRS to show the direction of the force on wire B due to the magnetic field produced by the current in wire A.
Wire A also experiences a force. State and explain which wire, if any, will have the larger force.
The direct currents in wires A and B are now replaced by sinusoidal alternating currents with equal peak values. The currents are in phase. Describe the variation, if any, of the force experienced by wire B.