How would I be able to produce a circuit that produces a very high current at a very low voltage? Would it be considered a reverse Tesla coil?
Method to create a high current and low voltage
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Mean free path of ideal gases
I have a box with a wall in mid dividing it in 2 sections, and the wall has a hole of diameter d. There is ideal gas in both sections at 150 K in one section and at 300 K in another. How am I supposed to calculate ratio of mean free paths in 2 sections.
My attempt: L ~ Volume / Number of...
Mean free path of ideal gases
My attempt: L ~ Volume / Number of...
Mean free path of ideal gases
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For animal lovers
Post your favorite animal pictures here!!
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Infinity of the Universe
We have a Universe that can be seen by Hubble maximum and we can imagine millions time more than that but if there is no boundary, there may be another millions of universe. Suppose we gather this all millions of universe and say this is a giant universe of universes and thus matter do not stop...
Infinity of the Universe
Infinity of the Universe
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Quantum optics/cavity QED refs?
I just got put on a project involving quantum optics, but have a background in semiconductor transport physics/electronic structure of materials. Does anybody know of a good textbook in this area, covering topics such as, say, the Jaynes-Cummings model?
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Probabilities with a Bell's state
If we consider a singlet state : $$(|+-\rangle-|-+\rangle)/\sqrt{2}$$.
And operators $$A=B=\textrm{diag}(1,-1)$$
I saw in a lecture that we can consider $$A\otimes B$$, it has multiple eigenvalues 1 and -1.
It was then said : we can choose orthonormal basis vectors in each eigenspace.
Hence...
Probabilities with a Bell's state
And operators $$A=B=\textrm{diag}(1,-1)$$
I saw in a lecture that we can consider $$A\otimes B$$, it has multiple eigenvalues 1 and -1.
It was then said : we can choose orthonormal basis vectors in each eigenspace.
Hence...
Probabilities with a Bell's state
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Emission line core in sunspots
What makes the core of some chromospheric lines such as the transition at 8542 A of the infrared Ca II triplet appear in emission in the dark umbra of sunspots?
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Infographic Article Showing Land Use in US
This Bloomburg article uses an set of interesting graphics (based on a variety of government data) to display how land is used in the US, usually down to pixels of 250,000 acres.
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HEPA filters and air purifiers for allergy relief?
My wife and some of my friends have been experiencing a spike in moderate allergy symptoms (Sx) this past week or two, and I was wondering if adding a HEPA air purifier at home in our bedroom would help. This recent PF thread discussed air purifiers, but not really from an allergy perspective:...
HEPA filters and air purifiers for allergy relief?
HEPA filters and air purifiers for allergy relief?
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Mathematics in Africa is on the rise.
Here's an interesting article by the AMS about mathematics in Sub-Saharan Africa. Also note the quotation on top:
Mathematics knows no races or geographic boundaries; for mathematics, the cultural world is one country. (David Hilbert)
Mathematics in Africa is on the rise.
Mathematics knows no races or geographic boundaries; for mathematics, the cultural world is one country. (David Hilbert)
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Destructive interference for distance-specific illumination?
From a practical standpoint, can we combine two (or more) lasers tuned to almost-but-not-quite identical frequencies to create distance-specific illumination? For instance, say we have a 1 micron laser and a 0.9999 micron laser which we combine through some beam-combiner optics. In theory I...
Destructive interference for distance-specific illumination?
Destructive interference for distance-specific illumination?
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Different approximations for the same problem
Hello I am looking at Stat Mech problem 2 from here (page 8) with solution here. I am confused about their approximations. They are all valid, but they are...
Different approximations for the same problem
Different approximations for the same problem
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Troubles understanding slow-roll conditions in Inflation
I've been reading up on inflation, and have arrived at the so-called slow roll conditions $$\epsilon =-\frac{\dot{H}}{H^{2}}\ll 1\; ,\qquad\eta =-\frac{\ddot{\phi}}{H\dot{\phi}}\ll 1$$
I have to admit, I'm having trouble understanding a couple of points. First, how does ##\epsilon\ll 1##...
Troubles understanding slow-roll conditions in Inflation
I have to admit, I'm having trouble understanding a couple of points. First, how does ##\epsilon\ll 1##...
Troubles understanding slow-roll conditions in Inflation
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Toroid with Air Gap magnetostatics problem
1. The problem statement, all variables and given/known data
consider a toroidal electromagnet with an iron ring threaded through the turns of wire. The ring is not complete and has a narrow parallel-sided air gap of thickness d. The iron has a constant magnetization of magnitude M in the...
Toroid with Air Gap magnetostatics problem
consider a toroidal electromagnet with an iron ring threaded through the turns of wire. The ring is not complete and has a narrow parallel-sided air gap of thickness d. The iron has a constant magnetization of magnitude M in the...
Toroid with Air Gap magnetostatics problem
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How is e^ikx a plane wave?
In these notes, https://ocw.mit.edu/courses/physics...-2016/lecture-notes/MIT8_04S16_LecNotes11.pdf, in the middle of page 5, it is mentioned:
We will be interested in bound states namely, energy eigenstates that are normalizable. For this the energy E of...
How is e^ikx a plane wave?
We will be interested in bound states namely, energy eigenstates that are normalizable. For this the energy E of...
How is e^ikx a plane wave?
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Other linear fitting than least squares
I'm analysing some data and my task is to get a line that best fits the data, using least square I'm getting these dashed curves (red and blue) with low correlation factors. Is there another method that takes into consideration the amount of data placed into the direction of a line?...
Other linear fitting than least squares
Other linear fitting than least squares
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How certain is dark matter?
How certain are scientists that the solution to the dark matter problem is a new, unknown particle (or more)? Theories that eliminate the need for new particle(s) and suggest modifications to the current understanding of gravity seem to get less attention. Why is that?
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Curriculum and book thoughts -- Lawyer looking to go back to school for a degree in Physics
Hello there!
As the title of this thread suggests, I am looking for recommendations in terms of identifying the areas and skills that I should be working on and the materials that I would need to do so.
But first, please allow me to give you a little bit of context to work with. Both my...
Curriculum and book thoughts -- Lawyer looking to go back to school for a degree in Physics
As the title of this thread suggests, I am looking for recommendations in terms of identifying the areas and skills that I should be working on and the materials that I would need to do so.
But first, please allow me to give you a little bit of context to work with. Both my...
Curriculum and book thoughts -- Lawyer looking to go back to school for a degree in Physics
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Efficiency prediction (minimum versus average)
I am trying to determine the efficiency of a light source for treating plants. When using the light source, there is an equal probability of encountering two different plant species.
The light source has a certain electro-optical efficiency ##\eta_{\text{eo}}##. And each plant type has a...
Efficiency prediction (minimum versus average)
The light source has a certain electro-optical efficiency ##\eta_{\text{eo}}##. And each plant type has a...
Efficiency prediction (minimum versus average)
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A Few Stock Dividend Questions
https://www.nasdaq.com/symbol/antm/dividend-history
1.) How do you read dividend information from a company's financials? E.g., The link above goes to Anthem (health insurer)'s dividend info. page. I see that there are quarterly dividend payments.
Under "Cash" - is that the...
A Few Stock Dividend Questions
1.) How do you read dividend information from a company's financials? E.g., The link above goes to Anthem (health insurer)'s dividend info. page. I see that there are quarterly dividend payments.
Under "Cash" - is that the...
A Few Stock Dividend Questions
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