A conducting rod lies across two horizontal, parallel conducting rails connected to a battery and a switch. The rod is positioned in the region between the North and South poles of a magnet, with the North pole above the rod and the South pole below it. When the switch is closed, the rod experiences a force and moves to the right. Which of the following modifications would cause the rod to move to the left?
Use a stronger magnet with the poles in the same positions.
Reverse the connections to the battery terminals and exchange the positions of the magnet's poles.
Reverse the connections to the battery terminals while keeping the magnet poles in their original positions.
Turn the conducting rod around so its ends are swapped.
275 exam-style questions on CIE IGCSE Physics 4.5 Electromagnetic effects, covering 4.5.1a Electromagnetic induction, 4.5.1b Direction of an induced e.m.f., 4.5.2 The a.c. generator, 4.5.3a Magnetic effect of a current and its applications, 4.5.3b Strength and direction of the field around wires and solenoids, 4.5.4a Force on a current-carrying conductor, 4.5.4b Force on beams of charged particles, 4.5.5 The d.c. motor, 4.5.6a Construction and operation of a transformer, 4.5.6b Turns ratio and current in a transformer, and 4.5.6c High-voltage transmission of electricity. Each one has a worked solution and a mark scheme showing where the marks go.