# All Questions

97 views

### Constant volume gas thermometer

Well, in the notes I took in thermodynamics' class I have a graph that plots Pressure of boiling point $P_b$ over Pressure of freezing point $P_f$ at constant volume in terms of Pressure of boiling ...
69 views

### Why does Ampère's force only linearly depend on the distance between the two wires?

When we encountered Ampère's force law our professor stated: In the formula of the magnetic force you don't find $r^2$ as in the gravitational and the electric one because while those directly ...
35 views

### Modular S matrix in 2D rational conformal field theory

The modular $S$ matrix in 2D CFT is defined by $$\chi_a(-\frac{1}{\tau})=S_{ab} \chi_b(\tau).$$ Can $S$ depend on the modular parameter $\tau$?
243 views

### Mølller scattering

I came across Mølller scattering today (which is just a fancy name for electron-electron scattering. I'm confused as to why there are two tree level Feynman diagrams for this process: Check out the ...
258 views

### How to arrange mirrors so I can't see myself?

If I wanted to surround myself with mirrors how would I need to arrange them so that if I stood in the middle of them I couldn't see myself in any reflection? For simplicity let's just say we only ...
132 views

### Constant magnetic field attenuation by µ-metal (mu-metal)

I am interested in the magnetic field attenuation by µ-metal. Specifically shielding from earth's magnetic field $\boldsymbol{H}_E$ through closed cylindrical layers of such a metal, yielding an ...
93 views

43 views

### Resistor color code extrapolation [closed]

I can't help wondering: what should the color stripes be on these?
48 views

### What makes red giants big? [duplicate]

I read some about red giants and so far I understand red giants become exhausted of burning hydrogen in the core, so then start hydrogen burning at shell and may or may not be burning helium in the ...
61 views

### Traveling to Mars in 24 Days

I am trying to calculate an electromagnetic rail launch from the Moon but I need to know if humans can survive the launch. Please see the specs below. 150 miles of track Proposed final launch speed ...
516 views

### Water VS Soapy Water

I recently did an experiment. I have a cup of tap water, and a cup of tap water mixed with soap. I used an eyedropper to slowly drip drops of tap water onto a penny. Then I cleaned the penny, and ...
27 views

### Potential of 2 parallel plates

How can I write down a potential of 2 parallel plates (area $A$) with charge $+Q$, $-Q$ such that V(inf)=0 and V(in) is what I would expect, $Ed = Qd/A\epsilon_0$. Do I have to write a discontinuous ...
49 views

### How can you add an exactly one-atom-height layer upon your material?

So for example let's say I have a 2cm x 2cm x 2cm cube of gold powder. Now I want to add just another layer of 2cm x 2cm x 1 atom upon it. It's been a long time since I last read some physics but I ...
63 views

### Special Relativity - three body problem

I have a problem with solving three-body problem in special relativity. I know that in general this problem doesn't have good solution, but I have a specific case when it should be good answer. ...
32 views

### How does a, halftone screen work?

Forever I've seen explainations that say a halftone printing image is made by photographing through a screen. But I have yet to see explained how that does the trick. Apparently the screen is placed ...
224 views

### Magnetic Wire Doesn't conduct Electricity

I recently bought a 22 and 30 gauge loop of magnetic wire from radio-shack. The loops of wire were colored differently (if this makes any difference) and on the package it noted how these wires were ...
4k views

### Could someone intuitively explain to me Ohm's law?

Could someone intuitively explain to me Ohm's law? I understand what voltage is and how it is the electric potential energy and that it is the integral of the electric field strength etc. I also ...
47 views

### What's the relation between the type (Gender) of a balloon and its internal pressure

I'm working on a project about balloons and I need to know the relation between the gender of the balloon and its internal pressure. As far as I know, there are some parameters such as " Elasticity of ...
297 views

### Capacitance and voltage drops

Let's say that Switch $S$ is closed. I have a conceptual question: If a stream of particles acquire a potential difference upon exiting the battery, why will they lose some of that potential ...