iGCSE Physics (0625) 4.5.4 Force on a current-carrying conductor -Exam Style Questions Paper 2 - New Syllabus
▶️ Answer/Explanation
Detailed solution:
A current-carrying conductor in a magnetic field experiences a force whose direction depends on both the field direction and the current direction.
Since the magnetic field is constant but the current repeatedly reverses direction, the force on the wire must also alternate direction.
The force is present whenever there is a current (not just during the reversal), so it alternates between one direction and the opposite direction.
This matches Option A.
▶️ Answer/Explanation
Detailed solution:
The direction of the force on a current-carrying conductor in a magnetic field is governed by Fleming’s left-hand rule.
This direction depends on the relative orientation of the magnetic field and the current; reversing either the current or the magnetic field will reverse the direction of the force.
Options A and C (increasing current or field strength) only affect the magnitude of the force, not its direction.
Using an identical magnetic polarity maintains the original field direction, so the force direction remains unchanged.
Therefore, reversing the current is the action that specifically changes the direction of the force.
▶️ Answer/Explanation
Detailed solution:
Fleming’s left-hand rule gives the direction of force on a current-carrying conductor in a magnetic field.
Align the First finger with the magnetic Field (N to S), the seCond finger with the Current, and the Thumb shows the direction of the Thrust (Force).
Applying this rule to the described setup, the force is directed out of the plane of the page, toward the viewer.
This matches Option B: out of the page (toward you).