What is Planck's Quantum Theory?

This theory states that a system(refers to atoms, molecules or ions) can neither absorb nor emit radiation in a continuous manner. Rather, it could only absorb or emit radiation of discrete values.

Postulates 

Following are the postulates provided by Planck to support his theory:   

  • Planck assumed that radiation could be sub-divided into small and discrete chunks of energy.
  • This smallest unit or chunk of energy was given the name - "quantum". Hence this theory came to known as Planck's Quantum Theory.
  • The energy contained in a quantum of radiation was found to be directly proportional to the frequency of the same radiation in wave nature. 

=> E(energy) ∝ v(frequency)
=> E = hv

here, h is a constant called the Planck's Constant.
The value of h is 6.62607015 × 10−34 joule second.