First recognized in 1900 by Max Planck, it was originally the proportionality constant between the minimal increment of energy, E, of a hypothetical electrically charged oscillator in a cavity that contained black body radiation, and the frequency, f, of its associated electromagnetic wave. In 1905 the value E, the minimal energy increment of a hypothetical oscillator, was theoretically associated by Einstein with a "quantum" or minimal element of the energy of the electromagnetic wave itself. The light quantum behaved in some respects as an electrically neutral particle, as opposed to an electromagnetic wave. It was eventually called the photon. 

Classical statistical mechanics requires the existence of h (but does not define its value). Eventually, following upon Planck's discovery, it was recognized that physical action cannot take on an arbitrary value. Instead, it must be some multiple of a very small quantity, the "quantum of action", now called the Planck constant. Classical physics cannot explain this fact. In many cases, such as for monochromatic light or for atoms, this quantum of action also implies that only certain energy levels are allowed, and values in between are forbidden. QUESTIONS:

Q1:
1. Who was the first person to associate the minimal energy increment of a hypothetical oscillator with a "quantum" element of the energy of the electromagnetic wave?
2. Who discovered the relationship between the minimal energy increment of a hypothetical oscillator and a "quantum" element of the energy of the electromagnetic wave?
3. 
Q2:
1. When did Max Planck discover something about quantums?
2. What was the year of Max Planck's quantum discovery?
3. 
Q3:
1. What letter represents the energy associated with a "quantum"?
2. Which letter is used to designate the minimal energy increment of a hypothetical oscillator?
3. 
Q4:
1. What did the light quantum do?
2. What was the light quantum's behavior like?
3. 
Q5:
1. What can an electrically neutral particle be placed in opposition to?
2. What is the opposite of an electrically neutral particle?
3. 
Q6:
1. What name was later given to the light quantum?
2. What did the light quantum's name become?
3. 
Q7:
1. Who first discovered energy E?
2. Who was the first person to understand what Energy E was?
3. 
Q8:
1. What sort of action cannot be given an arbitrary value?
2. What kind of action is it impossible to attribute an arbitrary value to?
3. 
Q9:
1. What kind of value must physical action be given?
2. Which value has to be attributed to physical action?
3. 
Q10:
1. What else can a multiple of a very small quantity be called?
2. What's anotion name for many of a very small quantity?
3. 
Q11:
1. Can the "quantum of action" be called something else?
2. Is there another term for the "quantum of action"?
3. 
Q12:
1. What's another name for the "quantum of action"?
2. What else is the "quantum of action" called?
3. 
Q13:
1. Is the Planck constant widely understood in physics?
2. Is the Planck constant an easily explained phenomenon in physics?
3. 
Q14:
1. What does the Planck constant imply about energy levels?
2. What can we infer regarding energy levels from the Planck constant?
3. 
Q15:
1. What does the Planck constant imply about values in between?
2. What can we infer regarding values in between from the Planck constant?
3. 
