Photoelectric Effect

Einstein realized that photoelectric effect could be understood if the energy in light is not spread out over wavefronts but is concentrated in small packets or photons.

• Planck thought that although energy from an electric oscillator had to be given to EM waves in separate quanta, the waves themselves behaved exactly as in conventional wave theory.
• Einstein: Energy was not only given quantazatically but was also carried by waves in separate quanta.

2. Photoelectric Effect

$$ hv=KE_{max}+\phi $$