The battery clips do not indicate which is positive and which is negative. How can you determine the poles of a battery

The battery clips do not indicate which is positive and which is negative. How can you determine the poles of a battery with only a compass and a coil of wire?

To determine the poles of the battery, you need to connect a conductor to the battery and bring a compass to it. A magnetic field exists around the current conductor and the compass needle will deflect. By the steady position of the arrow, you can find the direction of the current, and from there the field of the battery poles.