The zeeman effect, in which energy levels of electrons are shifted and produce a corresponding split in spectral lines observed, is used to measure at the sun's surface.

Magnetic Field Strength

Explanation:

The effect of the splitting of the spectral lines of an atom into several of its components when a static magnetic field is present is referred to as Zeeman Effect.

The spectral lines here corresponds to the various discrete energy levels in the sun at which the emission and absorption of the different energy levels of the sun occurs.

The splitting of the spectral lines occurs due to the presence of the strong magnetic field on the surface of the sun.

Thus the Zeeman Effect is used to measure the magnetic field strength on the sun's surface.

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