is the mechanical separation of a mixture based upon the sizes of the mixtures components.

Sieving

Explanation:

Sieving is a mechanical separation technique which depends on the relative sizes of particles in the mixture.

A mesh is used to discriminate between particle sizes. Particles in the mixture which are larger than the mesh size do not pass through the sieve, hence particles whose size is less than that of the mesh are separated from the rest of the particles in the mixture.

since electrons are negative the answer is neagtaive