What causes electrons in a transmitting antenna to oscillate?

Electrons in a transmitting antenna oscillate due to an alternating potential difference applied across the antenna. This alternating potential difference creates a changing electric field, which exerts a force on the electrons, causing them to move back and forth.

When the potential difference alternates, it effectively pushes electrons in one direction, then pulls them back in the opposite direction. This oscillation of charge generates electromagnetic radiation. The frequency of this alternating potential difference determines the frequency of the electromagnetic waves emitted.

While static electric fields might influence charges, they do not cause oscillation; they create a constant force. Constant magnetic fields can influence charged particles as well, but without an alternating component, they do not cause oscillation. Gravitational forces, on the other hand, are negligibly small at the scale of atomic electrons compared to electromagnetic forces, and thus have no significant impact on their motion in antennas.