You will be given a definition of a task first, then some input of the task.
In this task you will be given a text passage from a trivia quiz. You should choose the category this question belongs to from these categories: History, Science, Social Science, Fine Arts, Literature. You can only choose one category, so if in doubt, please choose the closest match.

The real part of the Clausius-Mossoti factor determines the direction of the force exerted by this. The Wannier-Stark problem involves exactly solving the Schrodinger equation for a single electron in a crystal subjected to a constant, external one of these. By Faradays Law of Induction, the partial time derivative of the magnetic field is equal to the curl of this. Nonuniform ones can induce dielectrophoresis, and the integral of it with respect to distance is electrical potential. For 10 points, name this field that surrounds point charges, denoted E.
Output:
Science