# All Questions

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### What is the fraction of the incident intensity passing through polarized sheets?

Unpolarized light is incident on a set of three polarizing sheets as shown in the figure at right. The polarizing directions of the sheets make angles 10*, 55* and 85* to the vertical. what fraction ...
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### Specific heat at constant volume

Me and my friend came across this derivation is some lecture notes of our thermal physics module. We have been trying to calculate the partial differential of the internal energy but cannot get the ...
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### Would any interference maxima be missing in the double slit experiment?

An aperture in the form of a narrow slit of 0.9mm wide forms a diffraction pattern on a screen placed 6.0 meters away when illuminated with light of wavelength 600 nm; would any of the interference ...
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### Amplitude of electric field produced by satellite dish

A telecommunications satellite is in geostationary orbit and it has a 1 m transmitting dish optimised for coverage of Europe. If the output power from this dish is 100 W, very roughly estimate the ...
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### Contradiction (?): DNA ion mobility vs diffusion constant

There is a certain confusion about DNA ion mobility and diffusion constant in the literature. Consider double-stranded DNA ions in pure water. DNA ions are negatively charged due to phosphoric acid ...
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### What is the difference between Chiral anomaly, ABJ anomaly, and Axial anomaly?

I get confuse with these three terms: Chiral anomaly, ABJ anomaly, and Axial anomaly. I can not find standard definition of these three. Is there anyone can describe precisely?
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### What is the procedure to follow if I want to renormalize a given operator $\cal{O}$ or a given coupling?

Consider QED. I know that the renormalization constant of the mass can be obtained from considering the electron propagator, regularizing it and renormalizing it. I know that from this process we can ...
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### Why is the shadow of a wind turbine a bit slow at first then very quickly, etc. and not equivalent to the wings?

When I stand at a wind turbine and look at the shadow on the ground, the shadow is a bit slow at first then very quickly, etc. Very strange.
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### How exactly analyticity of S-matrix comes from causality principle?

Recently I've read that analyticity of S-matrix ($S(k)$, where $k$ corresponds to momentum, may be analytically extended into complex values of momentum) comes from causality principle. How to prove ...
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### Why air conditioner, dehumidifier, and heater all can lower the relative humidity?

I think so far I understand it this way: why is humidity in Asia 75%, and humidity in California 82%, but California feels dry, and Asia feels humid. It is because there is something called Dew ...
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### Relation of current with frequency and voltage

I tried to solve a numerical problem but I got stuck and I think it very necessary I will drwa certain basic conclusions when I would found its solution. The question is: An incandescent lamp takes ...
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### Derivation of impedance matching formula

When matching impedances with a quarter wavelength coupler, how do I derive that its impedance has to be $$Z_2=\sqrt{Z_1 Z_3}$$ where $Z_1,Z_3$ are the impedances of the adjacent materials?