The photoelectric effect is the emission of electrons from a material when light of sufficient frequency shines on it. Einstein explained this phenomenon using the concept of photons, showing that light energy is quantized.

Key Formulas:

• Photon Energy: E = hf = hc/λ
• Photoelectric Equation: K_max = hf - φ
• Work Function: φ = hf₀
• Threshold Frequency: f₀ = φ/h
• Stopping Potential: K_max = eV₀

Units:

• Energy: J, eV
• Frequency: Hz, THz
• Wavelength: m, nm
• Potential: V

Applications:

• Photoelectric cells and solar panels
• Light sensors and photomultiplier tubes
• Quantum mechanics and atomic physics