The diagram below shows two long horizontal current-carrying wires, AAA and BBB.

The currents in the two wires flow in opposite directions.
Explain why wire BBB experiences a force and deduce the direction of this force.
State Lenz's law of electromagnetic induction.
Describe how a student can perform an experiment in the laboratory to show that the peak electromotive force (e.m.f.) EEE induced in the secondary coil of a transformer is directly proportional to the frequency fff of the alternating current in the primary coil, assuming the peak current in the primary coil is kept constant.