Why is it said that Einstein was not the first one to follow the photoelectric effect?

Einstein was not the first scientist to observe and study the photoelectric effect. However, he was the first to properly understand the nature of light and draw the correct assumptions from it. Physicists James Clerk Maxwell in Scotland and Hendrik Lorentz in the Netherlands had already proved the wave nature of light in the late 1800s. This was proven by seeing how light waves demonstrate interference, diffraction and scattering- which are common to all waves including water.

Einstein’s 1905 argument that light behaves as sets of particles (initially called quanta and later ‘photon’) was contradictory to the classical description of light as a wave. A completely new model of light was needed to explain the phenomenon. Einstein developed a model for this purpose and according to this, light sometimes behaved as particles of electromagnetic energy or photons. Though others had presented this theory before Einstein, he was the first to explain why it occurred and consider its potential.

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