Final answer:
The direction of the solar magnetic field in a sunspot can be determined using Hale's law, which relates to the polarity observed in sunspot pairs or groups, as analyzed through the Zeeman effect.
Step-by-step explanation:
A measure of the direction of the solar magnetic field in a sunspot is related to Hale's law. When examining sunspots, scientists utilize the Zeeman effect to determine the magnetic properties, including the field's direction. This phenomenon occurs when atoms under the influence of a magnetic field have their energy levels split, resulting in altered spectral lines when the electrons jump between these levels. Observations reveal that each sunspot pair or group will typically comprise one spot with a north magnetic polarity and another with the opposite. Furthermore, during a solar cycle, leading sunspots in one hemisphere share the same polarity, while those in the opposite hemisphere have contrary polarity, following Hale's law.