A student plots one field line by marking the positions of both ends of a compass needle. The student moves the compass so that its south-seeking end is on the previous north-end mark. What should the student do next?
Hold the needle in its previous direction, then mark its new north-end position.
Hold the needle in its previous direction, then rotate the bar magnet towards it.
Wait for the needle to settle, then rotate the bar magnet towards it.
Wait for the needle to settle, then mark its new north-end position.