Photoelectric effect and electrons

Lenard showed that light falling on certain metals causes electron emission and established the relationship between the light's wavelength and the emitted electrons' energy. The photoelectric effect made it appear that electrons existed in matter even when electric currents were not involved.
 Philipp Eduard Anton von Lenard Germany 1902 Photoelectric effect and electrons

Lenard showed that light falling on certain metals causes electron emission and established the relationship between the light's wavelength and the emitted electrons' energy. The photoelectric effect made it appear that electrons existed in matter even when electric currents were not involved.