Two charged particles held close together to each other are released. as they move, the force on each particle increases. therefore, the particles must have

Opposite charge

Explanation:

According to Coulomb's law: The magnitude of each of the electric forces with which two point-at-rest charges interact is directly proportional to the product of the magnitude of both charges and inversely proportional to the square of the distance that separates them and has the direction of the line that joins them. If the two charges have the same sign, the electrostatic force between them is repulsive; if they have different signs, the force between them is attractive.

layers of the earth affect the waves and these effects are seen on instruiments such as seimometers