Quantum Physics

1. UNIT - IV
QUANTUM PHYSICS

2. QUANTUM PHYSICS - SYLLABUS
Black body radiation – Planck’s theory (derivation) – Compton
effect: theory and experimental verification – wave particle
duality – electron diffraction – concept of wave function and
its physical significance – Schrödinger’s wave equation – time
independent and time dependent equations – particle in a one-
dimensional rigid box – tunnelling (qualitative) - scanning
tunnelling microscope.

4. FATHER OF QUANTUM THEORY
Max Planck
Born: April 23, 1858, Kiel
Died: October 4, 1947, Göttingen
Profession: Physicist
German theoretical physicist
Nobel Prize for Physics in 1918.

5.  Quantum physics is the study of the behavior
of matter and energy at the molecular,
atomic, nuclear and even smaller
microscopic levels.
 “Quantum” comes from the Latin meaning
“how much”.
 If refers to the discrete units of matter and
energy that are predicted and observed in
quantum physics. Even space and time,
which appear to be extremely continuous,
have smallest possible values.
What is Quantum Physics?

6.  A black body is one which absorbs the entire
heat radiations incident on it.
 When radiations are allowed to fall on such a
body they are neither reflected nor
transmitted.
 Such a body after absorbing the incident
radiations, on heating starts emitting
radiations which are independent of the
nature of the body and only depend upon
the temperature of the black body. These
radiations are known as black body
radiations.
BLACK BODY RADIATION

7. BLACK BODY RADIATION
 When the radiations enter in such a body through the hole they
suffer multiple reflections and are completely absorbed. Such a
body acts as a black body absorber.
 When such a body is heated through a high temperature it starts
emitting radiations called black body radiations through the
hole as shown in figure

8. ENERGY DISTRIBUTION IN A BLACK BODY SPECTRUM

9. ENERGY DISTRIBUTION IN A BLACK BODY SPECTRUM
Following facts were noted from the
graph.
 The energy distribution is not
uniform for any given
temperature.
 The intensity of radiation (E)
increases with increase in
wavelength and at a particular
wavelength its value is
maximum. Beyond this if the
wavelength increases the
intensity of heat radiation
decreases.
 The wavelength, at which maximum emission of energy takes place,
decreases with increase in temperature.
 For all wavelengths, an increase in temperature causes an increase in the
energy emission.

10. WIEN'S DISPLACEMENT LAW
 The wavelength, at which maximum emission of energy takes place,
decreases with increase in temperature.
 For all wavelengths, an increase in temperature causes an increase in the
energy emission.
Definition:
It states that the wavelength corresponding to the maximum energy is inversely
proportional to the absolute temperature.

11. RAYLEIGH JEAN’S LAW