plunk's quantum theory concept of continuous and discontinuous flow of energy and applications of planck's quantum theory firstly let me teach you the concept of excitation and de-excitation of electron let's consider an atom that this electron is present in first energy level according to bohr's atomic model energy is needed by this electron to jump from first energy level to second energy level let i provide 10.2 electron volt energy to this electron it will be excited and will move from first energy level to second energy level after some time this electron will be de-excited it will give off or radiate the same amount of energy 10.2 electron volt to the surrounding now listen carefully in old times a classical period scientists believe that an electron absorbs or loses energy continuously which is totally wrong in 1900 max planck put forward his famous quantum theory according to this theory electron absorbs or loses energy discontinuously which is hundred percent right this theory revolutionarized the signs and opened new doors for different discoveries now i am going to teach you the concept of continuous flow and discontinuous flow of energy believe me if you understand this concept you understand the planck's quantum theory which no one is teaching us in the school or college course remember that continuous flow of energy happens in our daily life while discontinuous flow of energy happens at microscopic level firstly let me teach you the concept of continuous flow of energy consider a ball present at certain height above the ground we know that it possesses potential energy now when this ball falls toward the ground its potential energy is converted to kinetic energy here comes the most important question can i change the value of potential energy or kinetic energy of this ball well the answer is yes it is in my control i can change its value the next question is how can i change its value well it is simple change the height of the ball to desired level and the values of potential energy and kinetic energy would be changed it means that it is in my control to change the values of potential energy and kinetic energy to 5 joule 6 joule 7 joule 8 joule etc therefore we say that in this case energy flow and continuous way our flow of energy is continuous because i can control it or i can change now coming to the concept of discontinuous flow of energy according to bohr's atomic model electron can reside in different energy levels like first energy level second energy level third energy level and fourth energy level like steps of a ladder now consider electron at highest energy level fourth energy level let this electron jumps from fourth energy level to third energy level when it jumps from higher energy level to lower energy level it loses a radiate energy let it loses 15 joule energy secondly this electron jumps from third energy level to second energy level and also loses 11 joule energy thirdly it jumps from second energy level to first energy level and it loses 4 joule energy now listen carefully i am interested that when an electron jumps from 4th energy level to 3rd energy level it should lose only 14 joule energy when it jumps from third energy level to second energy level it should lose only 13 joule energy and when it jumps from second energy level to first energy level it should lose only 12 joule energy i mean the flow of energy must be continuous 14 joule 13 joule 12 joule according to my wishes now let me ask you is it possible well here comes mix planck baba that it is not possible and it is totally wrong energy flow and discontinuous manner at microscopic level plunk baba says that when electron jumps from fourth energy level to third energy level it lose fixed amount of energy 15 joule energy in the form of discrete wave packet like this are just like a chocolate packet noted down that the word discrete means individually separate or unique we will learn more about wave packet later in this lecture secondly when an electron jumps from third energy level to second energy level it will lose another discrete wave packet of energy like this chocolate pack thirdly when an electron jumps from second energy level to first energy level it will again lose another discrete 12 packet of energy like this chocolate bag this web packet of energy is totally different from this wave packet of energy while this web packet of energy is also totally different from this wave packet of energy so max planck baba states that the energy of each wave packet is fixed or quantized for example this way packet has quantized energy of 15 joule this wave packet of energy has quantized energy of 11 joule and this wave packet of energy has quantized energy of 4 joule therefore energy discontinuously flow or the flow of energy is discontinuous because it is already fixed and we cannot control them hence noted down the concept of continuous flow and discontinuous flow of energy now let's understand the postulates of planck's quantum theory he states that energy absorbed or emitted by a body is in a discontinuous manner not in a continuous manner secondly he states that a body absorb a image energy and discrete wave packets these web packets are called quanta or in case of light it is called photon remember that quanta is plural and quantum is singular so note it down that whenever i say quanta quantum or photon in this lecture it will always mean wave packets now what is quanta are photon well photon or quanta is the elementary particle of light or we can say it is the basic unit of light it means that every light or radiation is made up of billions or trillions of photons photons are nothing but they are made up of electric field and magnetic field they have no charge they have no rest mass and they travel at the speed of light thirdly the energy of protons are quanta is directly proportional to the frequency e is directly proportional to mu for example consider blue photon and red photon the frequency of blue photon is high and the frequency of red photon is low so the energy of blue photon is high and that of rate photon is low now to eliminate the sign of proportionality we put h which is known as a planck's constant and its value is 6.626 into 10 to the power negative 34 joule second also we know that frequency is equal to c upon lambda so put the value of frequency in this equation we get e is equal to h into c upon lambda so remember that energy of photon depends upon frequency wavelength of wave number just noted down these postulates of planck's quantum theory finally let me teach you the application of planck's quantum theory we can easily understand and explain the monochromatic light and polychromatic light by the help of planck's quantum theory we know that monochromatic light means light of one color like red laser light while polychromatic light means light of many colors like sunlight this monochromatic red light is made up of one type of photon red photon all the photons have same wavelength same frequency and same energy therefore we see them red light while the sunlight is a mixture of seven lights like violet indigo blue green yellow orange and red the photon of foil it is different from indigo because they both have different wavelength frequency and energy similarly these all colors have different photons but overall they make up a white light which we can see as a sunlight here let me give you one last bonus tape photons are different from one another due to difference in frequency and wavelength so only these two parameters make different colors different waves etc i hope that you have understood the concept of planck's quantum theory