Werner Heisenberg introduced the uncertainty principle in 1927, which states that the position and momentum of a particle cannot be simultaneously measured with perfect precision. There is a minimum product of uncertainty between the two measurements. The principle arises because measuring one property, such as position, requires interacting with the particle in some way, such as using light, which disturbs the measurement of the other related property, like momentum. Heisenberg showed that the more precisely one property is measured, the less precisely the other must be known, as represented by the Heisenberg uncertainty principle equation. This describes the fundamental limit of what properties of particles can be known at the quantum scale.

1. Presented by- Ajay kant
M.Sc. 1st semester
Physics Department

2. HESINBERG UNCERTAINTY
PRINCIPLE
WERNER KARL HEISENBERG

3. CLASSICAL WORLD VS QUANTUM WORLD :-
CLASSICAL WORLD
• The observer is objective and
passive .
• Physical events happen
independently of whether
there is an observer or not .
• This is known as objective
reality .
QUANTUM WORLD
* The observer is not objective and
passive.
• The act of observation changes
the physical system irrevocably .
• This is known as subjective reality
.

4. INTRODUCTION:-
• Uncertainty principle was stated by Werner Karl
Heisenberg in 1927.
• This principle states that the position and momentum of a
particle can not be simultaneously measured with
arbitrary high precision. There is a minimum for the
product of the uncertainties of the two measurements.

6. HEISENBERG LIGHT AND ELECTRONS :-
* Measuring the position of a very small particle such as an
electron requires the use of short wavelength light (high
frequency, high momentum) . High frequency light will alter
the electron ‘s momentum . Use low frequency ( long
wavelength ) light and the position of the electron is not
well determined .

7. HEISENBERG PRINCIPLE – EQUATION : -
• The Heisenberg uncertainty has several forms . We denote the uncertainty in
momentum and position.

8. WHY THIS HAPPENS :-
• In the world of very small particles, one can’t measure any property of a particle
without interacting with it in some way and this interaction changes related property .
## Measuring p and x of electron –
• so to determine the position accurately it is necessary to use light with a short
wavelength .
• By Planck's law E = hV , a photon with a short wavelength has a large energy .
• So will give a large kick to the electron .
• But to determine its momentum accurately, electron must only be given a small kick .
• This means using light of long wavelength.

9. *Qualitatively if an indentical experiment involving an electron is
performed many times and in each the position of electron is
measured then for same momentum measurement of position will be
different each time .
• If x is average then standard deviation gives

10. MATHEMATICS EXPRESSION:-

11. SMALL UNCERTAINTY IN X . LARGE UNCERTAINTY IN X .