What does Stokes Law describe in the context of electrophoresis?

Stokes Law is fundamentally concerned with the motion of particles in a fluid, specifically illustrating how the velocity of a sphere in a viscous medium relates to the forces acting on it. In the context of electrophoresis, particularly when separating charged particles such as nucleic acids or proteins, the law helps explain how the charge of the particles and the strength of the electric field influence their movement.

When a substance is placed in an electric field, it experiences a force proportional to its charge. Simultaneously, the interaction of the substance with the medium (usually a gel or buffer) provides resistance to its motion, which can be characterized through Stokes Law. The balance between these forces determines how quickly different molecules migrate through the gel.

This connection clarifies that the migration rate is affected not only by the particle's charge but also by the strength of the electric field. Hence, the correct answer highlights the relationship between charge and electric field strength, which is critical for effective separation during electrophoresis.

In contrast, the other choices do not align with the fundamental principles described by Stokes Law in the context of electrophoresis. Temperature effects, pH on DNA stability, and sample purity do not directly pertain to the basic motion dynamics as outlined