Physics Questions, Problems & Solutions : TransWikia.com ~ Page 624

Why does quantum analogue of current density operator $mathbf j = rho mathbf v$ involve an anti-commutator?

I am reading through Luttinger's "Theory of Thermal Transport Coefficients". In equation (1.14), the charge-density operator is defined as$$rho(mathbf r) = esum_j delta(mathbf r-mathbf r_j).$$...

Asked on 01/24/2021

2 answer

Computation - can you compute the gradient, Laplacian, divergence and curl of any function?

In my physics class, we are currently studying gradient, Laplacian, divergence, and curl, and we have a problem that states to compute all four of these (I.e., (1) gradient, (2)...

Asked on 01/24/2021

1 answer

Accelerometer and Static Force

I'm studying the principles of accelerometer and given below is what is stated in LiveScienceAn accelerometer is an electromechanical device used to measure acceleration forces. Such forces...

Asked on 01/24/2021

2 answer

Why does Einstein's theory of specific heat fail only at one extreme of temperature?

Why does Einstein's theory of specific heat of solids work well at high temperatures but fail at low temperatures?...

Asked on 01/24/2021 by Soumita

1 answer

4-Vector Gradient and Contravariant Derivative

I am self-studying General Relativity, and the course of study I am following has started to introduce me to index notation. The texts I am using (Carroll, Schutz) begin with...

Asked on 01/24/2021 by Essenbee

2 answer

What experiment confirms $mathbf{J}^2 = hbar^2 j(j+1)$?

I learned that if we measure the spin angular momentum of an electron inone direction $J_z$, we get $pm frac{1}{2} hbar$. But if we measurethe...

Asked on 01/24/2021 by 30tah8uu

4 answer

Andromeda & Milky Way Merger: Gravitational Waves

When the Andromeda galaxy and Milky Way merge in the future, the super-massive black holes at their respective galactic centers will likely eventually merge. Similarly to the gravitational waves detected...

Asked on 01/24/2021

2 answer

Do gluon jets occur spontaneously in the real world, or only in a particle accelerator?

In this article by Matt Strassler, he says "A struck quark, like any accelerated particle, will radiate. A suddenly accelerated quark will radiate many gluons. ...

Asked on 01/24/2021

1 answer

Energy conservation for the beam splitter from first principles

Let's consider a (cubic) beam splitter with two electric input fields $E_1,E_2$ and two electric output fields $E_3,E_4$ as illustrated in the figure below. ...

Asked on 01/24/2021 by bodokaiser

1 answer

What do people actually mean by "rolling without slipping"?

I have never understood what's the meaning of the sentence "rolling without slipping". Let me explain. I'll give an example. Yesterday my mechanics professor introduced some concepts of rotational dynamics....

Asked on 01/24/2021

10 answer

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