Electrostatic induction
Electrostatic induction is the phenomenon in which a charged object causes a change in the electric field of a nearby neutral object, resulting in a separation of charge on the neutral object. This can be either an attraction or repulsion of the neutral object’s charges, depending on the type of charge on the inducing object.
Electroscope experiment
When the negatively charged rod is brought close to the end of the metallic wire of the electroscope experiment, the foil leaves of the electroscope will move away from each other due to the repulsive force of the negative charge. This is because the metal wire is connected to the ground and will become negatively charged from the electron transfer from the rod. This causes the leaves of the electroscope to move away from each other, indicating the presence of a negative charge.