Creating a uniform magnetic field
3 marks · NormalA student records the direction a magnetic compass points at different places between two bar magnets with unlike poles facing each other. The compass needle always points straight from one pole to the other across the gap. What does this suggest about the magnetic field in this region? Explain your answer.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
Also accept: The compass aligns with the magnetic field; its unchanging direction in the gap shows that the magnetic field is uniform there (constant direction and strength).
Common mistakes: Not relating compass direction to field direction; Forgetting the meaning of 'uniform'.
Show mark scheme and worked solution
Marking points
M1 · 1 mark · Links compass direction to field lines.
B1 · 1 mark · Explains that a constant compass direction means a constant field direction.
B2 · 1 mark · States that the field is uniform in the region between the poles.
Worked solution
A magnetic compass always aligns with the local magnetic field. If the direction never changes between the poles, this means the field lines are straight and parallel — so the field is uniform in that region.