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0

A capacitance bridge setup is good. One branch contains the known variable capacitance and a resistor. The other arm a resistor and the ferroelectric material. Adjust the known for null output.


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A simple way to do this requires an LCR (inductance, capacitance, resistance) meter, an oven/furnace/hotplate, and a thermocouple. With an LCR meter, you can measure the capacitance as well as the loss tangent, $ \delta $ at the same time. If you attach a thermocouple to the sample, and ramp the temperature slowly (less than 1 Celcius/min), you can measure ...


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A symmetric error in magnitude is not a symmetric error in flux. Put in the biggest value and smallest value of mc and use the two limits as an asymmetric flux error.


-1

try to use LTM method to measure ohmic contact between metal and semiconductor?


0

You can start by assuming that, if there's smoke, then the flame is not complexly extinguished yet. I suppose it's possible that the "smoke" is simply vaporized wax that is condensing, and not combustion products, but it's more likely there is still some combustion going on. Either way, the air mixed in with the smoke is hotter than the surrounding air ...


0

A zero-field-cooled/field-cooled split in the magnetic susceptibility vs. temperature doesn't have to be superparamagnetism. In the case of superconductors, if we apply a field to the material and cool past T$_c$, some flux can be trapped inside, but if we cool first and then apply field, that flux will be shielded away, resulting in greater diamagnetism.


0

I think you just need to treat two forces separately relative to each body as $\vec{F}_1=-\vec{F}_2$ and $\lvert|\vec{F}_1\rvert|=\lvert|\vec{F}_2\rvert|$. Having in mind that $\vec{F}_1(t),\vec{F}_2(t)$ both are functions of time because the motion goes with constant acceleration.


0

In the equation $F_f=\mu F_N$, where $F_f$ is the frictional force, $F_N$ is the normal force, and $\mu$ is the coefficient of friction, $\mu$ is sort of a way of expressing the quantity that you're looking for. You ask why this equation does not include an expression of the "roughness" of a surface, but it's not obvious to me how you would concisely ...


1

Even I didn't get you but I may help you how much I can by describing your case. Your case have two bodies which are being rubbed against each other in opposite direction with constant acceleration. The definition of friction is, "The resistance which either one of the bodies offers to this motion is called the force of friction and is said to be due to ...


1

Apart from the overdrive (saturation), the imperfections you see are laser speckles. It is an interference effect produced by imperfections inside your laser, possibly involving some dust or back-reflections. If you use cheap diode lasers, you will almost always get some of these, even from just the bare laser chip. There is a trick to clean up your beam: ...


0

The point of EPR is that you can learn about the B field in the neighborhood of an unpaired electron. You do this by applying a magnetic field, which generates an energy diffrence between the electron's spin up and spin down states. You measure this difference by finding the frequency of light that is absorbed. To a first approximation, $h\nu = g_e\beta ...


1

There is in fact a change in slope - you can see this when you fit a straight line through the data, then subtract it to look at the residuals: It seems that the first three data points lie on a steeper curve than the remainder - as though something changed in the setup (did thing heat up?) Residuals plots are an essential tool when you analyze data that ...


0

Do you have access to a dynamic signal analyzer or similar? My most recent setup involves locking in to a signal from a split photodiode that is either singly or doubly modulated. We chose our base modulation frequency by looking at the noise spectrum -- our photodiode when illuminated with a DC signal looks something like this: There's a ton of ...


0

This is pretty straight forward. All you need to do is measure the capacitance of the sample at constant frequency and at different temperatures. Imagine the sample as a parallel plate capacitor of thickness D and area A. Now Dielectric constant E = C D/A. With these calues you can plot the values w.r.t different temperatures and arrive at your curie ...


0

According to the Rule of Succession, the probability is 3/4. Or (successes+1) divided by (attempts +2). See: http://en.wikipedia.org/wiki/Rule_of_succession This is just an approximation.


2

The first part of the question If a theory gets two predictions right, how likely it is that the rest of the predictions are true too? << can not be answered since even the wrongest assumption can lead to 2 right predictions (and an uncounted bunch of wrong ones). Two opposite theories can have two simililar predictions which of course does not ...


2

I have demagnetized materials to try to eliminate magnetic fields from experiments. I took a coil of wire and passed AC mains through it to create an oscillating magnetic field - The AC was connected through an AC transformer like the one in the picture. slowly over time the voltage was reduced so a smaller and smaller magnetic field was used. To ...


1

You should take an electromagnet that operates on some frequency (tens of Hertz) and creates enough large magnetic field to magnetise your permanent magnet. Then you switch on your electromagnet in the vicinity of the permanent magnet and go slowly back from the permanent magnet at the distance of several meters. After this the permanent magnet should be ...


1

Relativity of simultaneity is a logical consequence of c's invariance. Time order reverseals have not been tested directly as far as I know, but since the invariance of c from which the relativity follows has been tested in a lot of experiments I would say that the thought experiments regarding this issue are solid.


3

I can't find details on the pulse energy and duration of the LCLS, but it's entirely plausible the power could be greater than the national grid of a large country. The power is energy divided by time, and if the pulse length is very short then even a modest pulse energy produces an astronomically high power. For example the laser at the National Ignition ...


0

There are some other options I can add. By using two cylindrical lens you can build a beam expander that only expands in one direction, thus correcting for the elongation of the beam. Once you have corrected for this you can then focus the beam on to a pinhole spatial filter. This would only partially work since the laser needs to have a Gaussian profile ...


1

The hydrogen molecule where the proton spins form a spin singlet $$ \left|s_1,s_2\right> = \frac{ \left|\uparrow\downarrow\right> - \left|\uparrow\downarrow\right> }{\sqrt2} $$ differs in energy from the spin triplet with $$ \left|s_1,s_2\right> = \frac{ \left|\uparrow\downarrow\right> + \left|\uparrow\downarrow\right> }{\sqrt2} $$ by a ...


4

It's really complex, and the answer from Shep is a bit imprecise. Ice at temperatures just below freezing has the remarkable property of not being frozen on the surface. There is a extremely thin layer of liquid water on the surface. How thin? 70 nm at 272 K, but only 10 nm at 262 K. This water layer can act as a lubricant, but with less lubricant the ...


6

It's only "sticky" when you stick it to something that was initially warmer than freezing. Let's say you stick your finger against a (very cold) ice cube. Two things happen in sequence: The heat from your finger transfers into the ice and melts it slightly, forming a thin water layer. The heat dissipates further into the cube, and the water refreezes. ...


2

A very simple example of electromagnetism in curved spacetime is the observed bending of light due to gravitational fields. Usually this is presented as the statement that "photons follow null geodesics." This statement can be derived in a geometric optics approximation to Maxwell's equations in curved spacetime (i.e. it is not just an additional postulate ...


1

I think I actually have an answer to this question even though I put a bounty on it. The idea is that the amplitude is maximal when the $W$ bosons are produced on-shell (since the propagators are the largest in this limit). This allows us to treat the creation of the $ W $'s separately from the rest of the diagram. The momenta of the particles in the lab ...


11

Classical electrodynamics is certainly studied in curved spacetimes to understand real phenomena. What better place for gravity and electromagnetism to work together than the ionized, magnetized plasma surrounding an accreting black hole? In particular, we observe quasars with extremely powerful relativistic jets. Quasars are the supermassive black holes at ...


0

For what it's worth, you might want to look up the original paper on the theory of helical diffraction: "The structure of synthetic polypeptides. I. The transform of atoms on a helix" W. Cochran, F. H. Crick and V. Vand, (1952) Acta Crystallographica 5, 581-86. This is the seminal work that allowed Crick and Watson to deduce the DNA structure. It is not a ...


3

Usually this is called "hysteresis" - a bit of "memory" of the last state (definition from Google): the phenomenon in which the value of a physical property lags behind changes in the effect causing it, as for instance when magnetic induction lags behind the magnetizing force. It can also (in the case of mechanical instruments) be known as "backlash". ...


7

Short answer: you don't. Slightly longer answer: You're using beams of particles, and you focus each of them as much as you (practically1) can so that the particles in each beam are reasonably close together. The result is a wide variety of interaction distances from far apart through near misses to closer interactions still. You mentioned electrons ...


0

What happens when you place your finger in a flame is that energy is transferred from a hot gas to the mass of your finger. This transfer of energy takes time. I guess this transfer is primarily through thermal conduction but the arguments probably apply for radiated energy too. The time it takes to transfer a given amount of energy into a given volume of ...



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