The formula is simple, it's flux/area. So in case of a sphere its flux/4π*r^2.

But my question is what exactly does...

Irradiance at a point on a surface]]>

Why do diamonds lose their sparkle in water?]]>

SU(5), 'Standard Model decomposition', direct sum etc.]]>

How to calculate Toroidal Core Maximum VA capacity]]>

Under such cases, the planarity is broken and resonance is no longer possible between attached group and benzene hence the charges have to maintain their...

Acidity due to ortho effect in benzene]]>

Can you guys provide a proof of the conservation of etendue (simple/memorable is preferred, if possible!) and a few realistic, practical examples just so I can get the hang of the ideas and the calculations? Much appreciated.]]>

$$\mathcal M_i=\gamma_{ij}D_k\pi^{kj},~~~~~~~~~~(1a)$$ or equivalently

$$\mathcal M_i=D_k\pi^{k}_i,~~~~~~~~~~(1b)$$ where

##\pi^{ij}=-\gamma^{1/2}\left(K^{ij}-\gamma^{ij}K\right)~##, ##K=\gamma^{ij}K_{ij}~##, ##\gamma=\det...

What is right expression for momentum constraint in GR?]]>

I know how to interpret a vector, inner product etcetera in one Hilbert space. However, I can not get my head around how the direct product of two (or more) Hilbert spaces can be interpreted.

For instance, the Hilbert space ##W## of a larger system is spanned by the direct product of...

Interpretation of direct product of Hilbert spaces]]>

Thanks :)]]>

1. The problem statement, all variables and given/known data

Here is the theorem (begins end of page 1), it is not my course but I have almost the same demonstration :...

[Statistics] Factorisation theorem proof]]>

The explanation which is usually given as to why there is a precession, is that the torque is perpendicular to the angular momentum and the angular momentum changes in the direction of...

2 Questions About the Gyroscope Effect]]>

The Hamiltonian for a particle in a magnetic field can be written as

$$\hat{H} = \frac{1}{2}g\mu_B\textbf{B}\cdot\boldsymbol\sigma$$

where ##\boldsymbol\sigma## are the Pauli matrices.

This Hamiltonian is written in the basis of the eigenstates of ##\sigma_z##, but how is it...

How to change the Hamiltonian in a change of basis]]>

What do you consider to be the most interesting alien race?]]>

If a photon were trapped between two perfect mirrors...]]>

http://ocw.nthu.edu.tw/ocw/upload/8/256/Chapter_7-98.pdf refer to page 3

in the 2nd, 3rd pictures, i have problem of finding σx'

why cant use the...

finding shear and normal stress after rotation]]>

What is Dark Matter?]]>

So, for instance, gravity could be like water in...

Would a spread theory eliminate the need for dark energy?]]>

the P was is quite large on my seismo ... surface waves haven't arrived yet (0739 AEST 2139 UT)

http://www.sydneystormcity.com/seismograms.htm

Dave]]>

Find the Time period using First Integral]]>

New here, Really weird sight in sky, Explanations?]]>

Quantum and GR analogy?]]>

I have a linear integral (e^xsiny-2)dx + (e^xcosy+x^2)dy

y≥0

2x=x^2+y^2

I used Green's theorem and got:

∬ (e^xcosy+2x) - (e^xcosy) dy dx

x bounds: from 0 to 2

y bounds: from 0 to sqrt(2x-x^2)

After solving all that stuff I...

Stuck on this integral]]>

Any mechanics

Electricity...

What Physics degree would be best for me?]]>

This week, it is where the water meets the land.

Your photo must have, as its main subject, a scene where large bodies of water meets the land. This may be a beach, a dock, a harbor, a lakefront, etc. There must be a clear depiction of that boundary...

PF Photo Contest - Waterfront (7/30-8/5)]]>

Since this is a Physics Forum, our theme this week is related to that subject area.

In Intro Physics classes, we often use various examples to illustrate the basic physics principles. This includes the simple pendulum, Hooke's Law spring,...

PF Photo Contest - Intro Physics (7/23-7/29)]]>

Four point charges are placed at the corners of a square of side 1m as shown in Fig 18.54 Find

a) the electric field, and

b) the electric potential at the center of the square

Photo is attached

Electrostatics question]]>

Telescope Design]]>

In the case of an ideal, thin lens (free from any aberration), it does not matter which face of the lens is facing the object. The results will be identical.

What if the lens was an ideal (no aberration) thick less with the H planes, etc...? Would it matter which lens surface is...

Thick Lens focal length and surface facing the object]]>

I ask for help in solving the exercises in this project on applied linear algebra. The problem outlined in the project is one in which we are tasked with modeling the demise of a gambler.

I need help solving exercise 1 (in...

Gambler's ruin]]>

I am stuck trying to figure out the voltage gain of a cascode amplifier from a small signal analysis. The circuit seems to be under-determined for reasons I do not understand or maybe I am missing the perfectly obvious.

Here's my small signal model:...

Small signal analysis of a cascode amplifier]]>

Two loudspeakers, A and B, are driven by the same amplifier and emit sinusoidal waves in phase. Speaker B is L = 2.00 m to the right of speaker A. The frequency of the sound waves produced by the loudspeakers is f = 206 Hz....

Interference of sound]]>

What am I missing?]]>

In my book, I was told that when an element is subjected to pure shear stress, equalibrium required that equal shear stress must be developed on four sides of the element...these stresses must be

direction of shear stress]]>

When a conductor is charged by conduction, the electrons spread throughout the surface of the conductor. Doesn't this mean that the capacitor is storing this electricity? What prevents conductors from...

Why are conductors not used to store electricity?]]>

Consider the systems of 2kg and 5kg blocks. The 2kg block is resting upon a smooth frictionless horizontal surface and friction in pulley bearing is negligible. The 5kg block is suspended by a cord connected to the 2kg block....

Acceleration of pulley system]]>