I don't understand how Planck's equation can state that energy is quantized. in E = hv where E = energy of the photon h Planck's constant and v=frequency how can E have only discrete amounts? plancks constant is .. well.. a constant but isn't frequency a constantly varying or Infinitely variable quantity? If so, how can E have only certain values? (In the book "Advanced chemistry by Raymond Chang" it says that energy can come in packets which have energies of hv, 2hv, 3hv and so on... I'm having trouble understanding this as well..) thanks.