Physics

# Key Equations

PhysicsKey Equations

### 21.1Planck and Quantum Nature of Light

 quantum energy $E=nhf E=nhf$

### 21.2Einstein and the Photoelectric Effect

 energy of a photon $E=hf E=hf$ maximum kinetic energy of a photoelectron $K E e =hf−BE K E e =hf−BE$ binding energy of an electron $BE=h f O BE=h f O$

### 21.3The Dual Nature of Light

 momentum of a photon (deBroglie relation) $p= h λ p= h λ$