A horseshoe magnet is fixed beneath a sheet of paper. A student uses a plotting compass with a north-seeking tip and a south-seeking tail to trace one field line. The needle has settled and the student has placed a pencil dot at the north-seeking tip.
What should the student do before marking the next dot?
Move the compass so that the north-seeking tip covers the dot, then let the needle settle.
Move the compass one needle length towards the nearer pole, then let the needle settle.
Move the compass so that the south-seeking tail covers the dot, then let the needle settle.
Move the compass one needle length parallel to the paper edge, then let the needle settle.