# All Questions

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### why am i getting lower mass after melting iron dust?

I've been trying to melt iron dust for a long time but after melting I lose a lot of mass. Any idea what is causing this? I've used gas and electrical arc to melt the dust.
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### Gaining some intuition: Photon bunching

This is a very easy question: I'm in need of some intuition on the fact that, e.g. thermal sources, produce bunched photons. It is very easy to "undertand", without any quantum mechanics, why single ...
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### If cathode rays travel from the cathode to the anode how do they make zinc sulphide glow?

So I basically learned about cathode rays today, and I had a lot of questions in mind. So my textbook says cathode rays travel from the cathode to the anode. So it further says that to observe ...
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### Analysis of a system consisting of a leaking tank of water

The departure point is this problem: A water tank on wheels is moving over an horizontal trail with negligible friction. There is a small opening in one of the walls, at a depth of $h$ below the ...
3k views

### How do those T-shirts that change color in the sun work?

When I was a kid, I asked my dad about them and he said (not in so many words) that it was because sunlight and artificial light have different spectrums and they picked colors that reflect only the ...
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### Why does a bungee jumper continue to move downwards beyond the equilibrium position of the jumper and cord?

When a bungee jumper jumps, ignoring the mass of the bungee cord, the jumper initially falls in freefall before an inelastic collision occurs between the jumper and cord, and the cord extends as the ...
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### Diffractive peak for high-frequency scattering from a sphere with small index of refraction?

How does a transparent sphere's shadow fade as $n\to 1$? Consider radiation of wavenumber $k$ incident on a transparent sphere of radius $a$ and index of refraction $n$ in the limit $ka \gg 1$. ...
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### How to find the correlation function? [on hold]

I have an operator $\hat{a}(t)$, and the its correlation is given as: $$\langle\hat{a}(t)\hat{a}^{\dagger}(t^{\prime })\rangle=\delta(t-t^{\prime})$$ Then how can I find the correlation function in ...
21 views

### Does photon experience time? [duplicate]

According to the special theory of relativity, for all observers the speed of light is c. Any observer travelling at the speed of light c does not experience time. Hence even protons shouldn't ...
33 views

### How do you calculate the intensity of the $m$'th fringe in a Young's slits diffraction pattern? [on hold]

I'm preparing for an exam on wave optics and am struggling with part d) of this question: c) A beam of coherent monochromatic light (wavelength=500nm) is incident normally of a plane of two slits ...
55 views

### Vacuum expectation value in presence of a source

If a vacuum is translationally invariant i.e., $P^\mu|0\rangle=0$ or $e^{(\pm ip\cdot x)}|0\rangle=0$, we can express the the vacuum expectation value of a field as $\langle 0|\phi(x)|0\rangle$ as ...
17 views

### X-rays-Is the mass of electrons being converted into energy? [on hold]

Are electrons converted into energy in an x-ray tube?
28 views

### Dynamic energy of capacitors in circuit

If I have 3 capacitors and 1 battery in a circuit how should I connect them in order to have maximum dynamic energy, when I connect them with the battery? Parallel or in series?
27 views

### Can you pass cathode rays in a non vacuumed tube [on hold]

Is it possible to have a cathode ray discharge in a non vaccumed tube while having a low pressure?
48 views

### How does covering a hot bowl of soup prevent heat losses?

Recently I took out some soup to eat and got a call from a friend. I covered it with a plate and when i came back later, it was still hot. While i was eating, i wondered how does covering this hot ...
81 views

### Von Neumann entropy of mixtures of coherent states

I'm trying to calculate the Von Neumann entropy of statistical mixtures of coherent states. The problem is that such states are in general non-Gaussian, so one cannot follow the formalism developed ...
23 views

### Is it possible to get an analytic expression of the capacitance for this geometry?

Here is the geometry I'm talking about: Assume the red rectangle is at some constant potential V, like 10 Volts, and the blue is at ground. We can assume that the rectangles extend infinitely (to ...
35 views

### Balancing Orthogonal Forces on 2D plane with arbitrary placement [on hold]

I have a rectangular block in the xy plane with the center of mass that acts in the z direction at an arbitrary place in the plane. I also have 4 legs that support this weight underneath the block. ...
18 views

### Non-zero spin meson have ever seen experimentally? [on hold]

Have been ever shown ( in experiment) none-zero spin meson? We should have it?
17 views

### Lens and Mirror Grinding

I am actually grinding my own lenses ( I am trying). Now I have been continuously using the chordal stroke for atleast 3 hours but i am unable to see any depreasion be it convex or conacve on the tool ...
39 views

### can the behavior of light be explained on the basis of a single theory?

Can the behavior of light be explained on the basis of a single theory ? example, wave theory of light ,if not then why?
38 views

### According to the theory of relativity, (relativistic) mass of an electron changes when it moves at very high speed; how and why? [duplicate]

It is given that $$\mathbf m' = \frac{m}{\sqrt{1-\frac{v^2}{c^2}}}$$ How does (relativistic) mass change here?
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### Which elementary particles have been seen up to now?

Which elementary particles have been shown up to now? which one except Graviton, haven't seen? I need an update one, I am searching but I couldn't find. If anyone could answer me, I am so thankful.
10 views

### Transverse momentum [duplicate]

I'm having an introduction on detector systems in particle physics. The sources I read constantly talk about the measurement of "transverse momentum". However, I cannot find a definition of what is ...
11 views

### How do I decide what my x and y axes will be when given data on resistivity?

Ok so I have been given a table with 3 lots of information; the wire length, voltage, and current (and the cross-sectional area is also stated). It says to then determine the resistivity. I was ...
22 views

### Finding equivalent capacitance between A and B, [on hold]

Following is the question, asked is to find equivalent capacitance between A and B. I've tried couple of times and getting 7/3 micro farad as the answer while the correct answer is 8/3 micro farads. ...
19 views

### How much pascals is needed to lift a human? [on hold]

I wanna ask you that how much psi is required to lift a man 1000 metres up in the sky of weight 'bout 100 kgs??? I'm not much good at physics