A small compass lies on a desk, its needle settled pointing north. A bar magnet slides closer, and the needle swings away from north to a new direction. Something is turning it.
In the Fields topic you saw that magnetic field lines run from a magnet's north pole to its south pole outside the magnet. A compass makes those lines visible.
A compass needle is a small magnet mounted on a pivot, free to spin. Because the needle is a magnet, a magnetic field turns it.
The needle settles lying along the magnetic field line at the spot where it sits. Its north end points the way the field line's arrow points.
Move the compass to a new spot, and the needle swings to follow the field line there. So a plotting compass placed near a bar magnet maps the field, point by point.
What is a compass needle?
A plotting compass sits on a field line near a bar magnet. Which way does its north end point?
A plotting compass is placed beside a bar magnet, at a spot where the field line points east. Which way does the needle's north end point?
The needle is a small magnet, so the field turns it.
It settles along the line, with its north end pointing the way the arrow points.
The field line at this spot points east.
The needle's north end points east.
The same compass is carried to a spot where the field line points southwest. What does the needle do?
At the new spot, the field line runs in a new direction.
The needle swings until it lies along the line there.
The needle swings around and settles with its north end pointing southwest.
Jude says a compass needle turns because the needle is itself a magnet. Is Jude correct?
A compass needle near a bar magnet lies settled along the local field line. The magnet is turned end for end, reversing the field line's direction at that spot. What does the needle do?
The compass sits at the dot above the magnet. Which way does its north end point?
Omar says a compass needle near a magnet swings because the magnet attracts the metal needle like a paperclip, dragging it straight toward itself. Which statement corrects Omar?