# All Questions

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### Has someone measured that in the far field of radio waves, the electric and magnetic field oscillate synchronously?

That in near field both fields oscillating 90° displaced is obvious since in antenna rod a lot of electrons will be accelerated and and this oscillation of electric field is escorted by alignment of ...
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### Why does the Magnetic Flux Density B, saturates in a ferromagnetic material with increasing H?

I understand that the magnetization must saturate as more and more domains are aligned. But $B$ is still directly proportional to $H$, and hence it must increase linearly with $H$. But every book ...
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### Resulting force when bending plywood

My sister and I are working on a thesis in interior design on a plywood chair similar to the picture, where the red part bends. We are trying to work out how much the plywood would push back when a ...
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### Determine normal forces on tilted table [on hold]

A table with the mass m, the height a and the width b is resting on a tilted floor with the angle of rake $\alpha$. A block at A prevents the table from sliding. Determine the normal forces from the ...
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### Gamma matrices in Decay Calculations

I am trying to calculate the transition amplitude, $\lvert M^2\rvert$, for the process where a top quark (momentum p) decays to a bottom quark (momentum q) and a $W^+$ boson (momentum k). I am ...
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### The speed of air rising through a heated tube

I would like to get an explanations of an observed physical phenomena. When a metal tube is placed vertically and heated and the air inside rises, the speed of the air moving through the tube ...
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### Why is there zero point energy at absolute zero temperature? [on hold]

If we define the absolute zero as a temperature which there is no entropy in it so why should we have zero point energy?
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### What is the meaning of “ Ψ is not a measurable quantity in itself”?

I want to know that why the wavefunction Ψ as a complex quantity (i.e $A+iB$ form) in quantum mechanics and somewhere I have studied that Ψ is not a measurable quantity in itself that's why we ...
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### How to determine which object in a special relativity physics problem has proper time?

I'm having some difficulty determining which object/location should have proper time applied to it in relativity physics problems. Example: If an electron travels at 40% the speed of light then ...
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### Can a brane have infinite volume?

I'm asking this within the framework of brane theory. My intuition is that branes are objects with finite volume, but then how can they accomodate an Universe that is infinite in extent?
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### Electric field due to a finite line charge [on hold]

I was wondering what would happen if we were to calculate electric field due to a finite line charge. Most books have this for an infinite line charge. In the given figure if I remove the portion of ...
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### Polarization of light for a fast moving observer

For a fast moving observer the frequency of light becomes shifted due to the (relativistic) Doppler effect. But what about the polarization of the light? Could it be, that e.g. circular polarized ...
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### When will the pringles can fall?

When I'm pushing a tall, cylindrical object stood on its end (like a Pringles can) I can push it near its bottom, and it will slide forwards, or push it near the top, and it will topple over. So, ...
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### Why is energy in a system typically able to be described using quadratic expressions?

This might be more of an applied math question. Why is the energy of a system typically able to be described using quadratic expressions. Is there an underlying mechanic that drives this?
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### Current carrying conductor with a loop at a distance [on hold]

In Fig, there are an infinitely long conductive wire and a circle conductive loop C with the radius r and the number of turns n. The distance L between the wire and the loop is much larger than r, ...
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### Can you ever exert more downwards force than your weight?

So, because I'm a hardcore person, I risked all this afternoon by going out in the wind, the rain and the cold to construct a willow den. Yes, it seems a menial task, but it was actually quite ...