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[NOTES/EM-03005] Charged Particle In Electromagnetic Field


Expression for the Lagrangian for a charged particle in electromagnetic field is given. Gauge invariance of the Lagrangian furnishes an example quasi invariance under the gauge transformations.


kapoor's picture 24-03-26 22:03:15

[NOTES/QM-09008] Perturbation Expansion in Interaction picture


The equation \[i\hbar\frac{d U(t,t_0)}{dt} = H'_I(t) U(t,t_0).\] obeyed by the time evolution operator in the interaction picture is converted into an integral equation. A perturbative solution is obtained from the integral equation following a standard iterative procedure.


AK-47's picture 24-03-24 19:03:37

[NOTES/QM-09004] Stationary States and Constants of Motion


The eigenstates of Hamiltonian are called stationary states.In a stationary state all observable quantities are independent of time. The dynamical variables which commute with Hamiltonian are called constants of motion. The average values of constants of motion in  any state do not change with time. 


AK-47's picture 24-03-24 19:03:48

[NOTES/QM-09007] Interaction Picture of Quantum Mechanics

The interaction picture, also known as Dirac picture, or the intermediate picture, is defined by splitting the Hamiltonian in two parts, the free and the interaction parts. In interaction picture equation of motion for the observables is free particle equation. The state vector satisfies Schrodinger equation with interaction Hamiltonian giving the rate of time evolution.

AK-47's picture 24-03-24 19:03:00

[NOTES/QM-09003] Solution of TIme Dependent Schrodinger Equation


A scheme to solve the time dependent Schr\"{o}dinger equation \begin{equation} \label{eq01} i\hbar \dd{t}\ket{\psi} = \hat{H} \ket{\psi} \end{equation} is described. The final solution will be presented in the form, see \eqref{eq14} \begin{equation} \ket{\psi t} = U(t, t_0) \ket{\psi t_0} \label{eq16} \end{equation}where
\begin{equation}\label{EQ16A} U(t, t_0) \ket{\psi t_0} = \exp\Big(\frac{-i H(t-t_0)}{\hbar}\Big)\end{equation}


AK-47's picture 24-03-23 05:03:26

[NOTES/SM-01001] Thermodynamic Coodinates

kapoor's picture 24-03-20 15:03:27

[NOTES/CM-02003] From Newton's EOM to Euler Lagrange EOM

 Euler Lagrange equations are obtained using Newton's laws and D' Alembert's principle.

kapoor's picture 24-03-15 06:03:32

[NOTES/CM-02001] Limitations of Newtonian Mechanics

Some limitations of Newtonian mechanics are pointed out.

kapoor's picture 24-03-15 04:03:24

[NOTES/QFT-01001] Examples of Classical Fields

After recalling the analytical dynamics briefly, several examples of systems with infinite degrees of freed are given.

kapoor's picture 24-03-10 09:03:01

[NOTES/EM-07013] Conservtion of Electromagnetic Field Momentum.*

 


The equation of continuity appears in different branches of physics. It represents a local conservation law. In order to be consistent with requirement if special relativity every conserved quantity must come with a current which gives the flow of the conserved quantity across a surface and the two must obey equation of continuity. Taking the example of momentum conservation, we briefly discuss the interpretation of stress tensor giving flow of momentum per unit time as a surface integral. The surface integral, in  turn, gives the  force on the surface.


 

kapoor's picture 24-03-02 11:03:19

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