Magnetic fields
4 marks · NormalA student investigates the magnetic field around two bar magnets placed 5 cm apart with their opposite poles facing each other, as shown below.
Draw the expected pattern of magnetic field lines around the two magnets.
Explain why the field lines between the two magnets take the shape that they do.
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.
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(a) — · must show Field lines emerge from north poles and enter south poles, Curved lines connecting the facing poles in the center, No crossing of field lines, Lines are closer together in the center
(b) Field lines run from the north pole of one magnet to the south pole of the other because opposite poles attract, creating a strong uniform field between them. · must show opposite poles attract so field lines connect directly between, field is strongest and lines are closest together between facing poles
Common mistakes: Drawing field lines between similar poles; Field lines not connecting N to S
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Marking points
M1 (a) · 1 mark · Lines drawn emerging from north and entering south on both magnets, correctly showing overall direction.
M2 (a) · 1 mark · Lines connect directly between the two facing poles, arc between and outside, no crossing of field lines.
B1 (b) · 1 mark · States that opposite poles attract and this causes field lines to join directly from north to south.
B2 (b) · 1 mark · Describes that field is strongest and lines are closest together between facing poles.
Worked solution
Field lines go from the north pole of one magnet to the south pole of the other. They are closely spaced between the facing poles, showing a strong field there.
This happens because opposite poles attract, so the lines connect directly and the region between the poles is where the field is strongest.