What is Quantum Theory of Radiation ?

Quantum Theory of Radiation:This theory was proposed by German physicist, Max Planck in 1900, to explain the phenomena of black body radiations. According to this theory;

“Energy is emitted or absorbed by a body not continuously but discontinuously in the form of small packets or bundles of energy known as Quanta. The energy of a body can increase or decrease by 1,2,3,4,5,…..n quanta but not by fractions of a quanta."

Thus, the energy of radiation is proportional to its frequency and inversely proportional to wave length.

Solved Questions:

(1) Calculate the energy per mole of photon of electromagnetic radiations of wavelength 4000Å.

(2) Suppose 10–17 J of light energy is needed by the interior of the human eye to see an object. How many photons of green light (wavelength =550 nm) are needed to generate this minimum amount of energy?

(3) A bulb emits light of wave length 4500Å. The bulb is rated as 150 watt and 8% of the energy is emitted as light. How many photons are emitted by the bulb per second?

Practice Questions:

1. A photon of light of wavelength 6000 Å has energy E. Calculate the wavelength of photon of a light which has energy/photon 4E.                                                            

2. Calculate the wavelength, wave number and frequency of photon having its energy 5 electron volt.

3. Iodine molecule dissociates into atoms after absorbing light of 4500Å. If one quantum of radiation is absorbed by each molecule, calculate the kinetic energy of iodine atoms. (Bond energy of I₂ = 240 kJ mol^–1)                      

Answer Keys:                                

1.     Lemda-2= 1500 Å

2.     2.475 × 10^–5 cm, 4.04 × 10⁴ cm, 1.212 × 10¹⁵ Hz

3.     2.16 × 10^–20 J

Related Questions:

(1) What is the difference between 2p and 3p orbitals?

(2) Why are 2p orbitals higher in energy than 2s?

(3) Does 2s and 2p have the same energy?

(4) Calculate radial and angular node for 2p-orbitals.

(5) What are the difference between "Nodal surface" and "Nodal plane"?

(6) What are Zeeman and Stark effects? Were they explained by the Bohr’s theory?

(7) Which of the Hydrogen spectrum series found in visible range of spectrum?

(8) What are difference between "Isoelectronic" and "Isosters" species?

(9) What are the difference between "Kernel" and "Core" ?

A bulb emits light of wave length 4500Å. The bulb is rated as 150 watt and 8% of the energy is emitted as light. How many photons are emitted by the bulb per second?

 

Related Questions:

What is the difference between 2p and 3p orbitals?

Why are 2p orbitals higher in energy than 2s?

Does 2s and 2p have the same energy?

Calculate radial and angular node for 2p-orbitals.

What are the difference between "Nodal surface" and "Nodal plane"?

What are Zeeman and Stark effects? Were they explained by the Bohr’s theory?

Which of the Hydrogen spectrum series found in visible range of spectrum?

What are difference between "Isoelectronic" and "Isosters" species?

What are the difference between "Kernel" and "Core" ?

Suppose 10–17 J of light energy is needed by the interior of the human eye to see an object. How many photons of green light (wavelength =550 nm) are needed to generate this minimum amount of energy?

 

 Related Questions:

(1) The ionization energy of He+ is 19.6 10^-18 J atom^-1. The energy of the first stationary state of Li+2 will be :

(2) Show that the wavelength of a 150 g rubber ball moving with a velocity 50 m sec^-1 is short enough to be observed ..

(3) If an electron is present in n = 6 level. How many spectral lines would be observed in case of H atom ...

(4) Speed of helium atom at 300K is 2.40 x10^2 meter per sec. What is its wave length. (mass number of helium is 4)..

(5) K.E. of the electron is 4.55 x 10^-25 J. Its de Broglie wave length is ...

(6) The wavelength associated with a golf ball weighing 200g and moving at a speed of 5m/h is of the order.

(7) The ratio of wave length of photon corresponding to the alpha-line of Lyman series in H-atom and Beta-line of Balmer series in He+ is

(8) shortest wavelength of He+ ion in Balmer series is x, then longest wavelength in the Paschene series of Li+2 is

(9) The ratio of difference in wavelengths of 1st and 2nd lines of Lyman series in H like atom to difference in wavelength for 2nd and 3rd lines of same series is:

(10) If H+ (ion) is accelerated to a final velocity of 6.62×10+6 meter per second and error in velocity is 1% then find uncertainty in position is?

(11) What is the relation between Total energy (TE), Kinetic energy (KE) and Potential energy (PE) of Bohr's orbits?

(12) How to calculate energy of Bohr's orbits in term of Rydberg's constant