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Q&A

General Q&A about physics of any type and at any level

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62%
+3 −1
SI Units of wavefunction

What are the SI units of the wavefunction Ψ(x).I know that [Ψ(x)]^2 describes the probabilty of finding a quantum object at a certain quantum state but what about the wavefunction instead?

1 answer  ·  posted 1y ago by MissMulan‭  ·  last activity 18h ago by Anyon‭

80%
+6 −0
Why is it forbidden for two photons to turn into one?

In the context of quantum field theory, why is it impossible for two photons (or other massless bosons like gluons) to collide and produce a single photon? This kind of a process is supposed to be ...

3 answers  ·  posted 12mo ago by Technically Natural‭  ·  last activity 4d ago by dmckee‭

60%
+1 −0
Is there an expected upper bound on the processing abilities of quantum computers?

A computer can store some number $n$ of bits in memory, and it can perform some number $m$ of essential computational operations, such as addition or multiplication, and rewrite those bits to memor...

1 answer  ·  posted 3mo ago by Julius H.‭  ·  last activity 2mo ago by ariyadanesh‭

42%
+1 −2
In particle physics and string theory, what is mass?

We commonly say that something has a weight, which is synonymous with a mass. Things have a weight because the force of gravity is relative to something’s mass. Subatomically, what is mass? There ...

0 answers  ·  posted 3mo ago by Julius H.‭  ·  edited 3mo ago by Julius H.‭

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+3 −0
Does an ultrasonic air humidifier use energy less energy than a steam humidifier?

There are a couple different types of indoor air humidifiers. Most notably, the naive steam humidifier with a heating element, and then ultrasonic humidifiers. Now, heating water to create steam o...

1 answer  ·  posted 7mo ago by Iizuki‭  ·  last activity 7mo ago by Olin Lathrop‭

20%
+0 −6
How do I calculate which concentration of Vinegar is cheapest, before diluting it? [closed]

Presuppose that I need vinegar of $c$ concentration, where $c$ < any concentration listed below. Let $w$ be the price of water that I'll use to dilute. How do I deduce which concentration (of V...

1 answer  ·  posted 9mo ago by TextKit‭  ·  closed 8mo ago by Mithrandir24601‭

66%
+2 −0
Osmosis in a U-shaped tube with selective permeable membrane

Starting from the classical osmosis experiment, a U-shaped tube with a semi-permeable membrane, I would like to consider the case when the solute added to one of the compartments (labelled A) is co...

0 answers  ·  posted 10mo ago by Joce‭

42%
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To what extent does blender speed dissolve table salt + cold tap water?

At home daily, I need to mix my table salt + COLD tap water. As "Marine salts dissolve faster and more thoroughly when added to circulating water," I "use a powerhead to speed up mixing time — my V...

2 answers  ·  posted 1y ago by TextKit‭  ·  last activity 11mo ago by matthewsnyder‭

50%
+0 −0
How are gravitational waves derived?

Gravitational waves can be derived from the non-linear Einstein field equations and since they are by definition waves they must obey the wave equation: $u_{tt}=c^{2}u_{xx}$ but in General Rela...

1 answer  ·  posted 11mo ago by Volpina‭  ·  last activity 11mo ago by Mithrandir24601‭

25%
+0 −4
Why the water drop by a stick through bottle hole slow down? [closed]

Question I was wondering what force make drop slow down? Does every time a drop push toothpick back into bottle? And of course how to solve it. Struct This is a bottle be pierced by a wooden too...

0 answers  ·  posted 1y ago by Dead_Bush_Sanpai‭  ·  closed 11mo ago by ArtOfCode‭

60%
+1 −0
Understand intuitively 4th boundary condition of gravitational wave

Suppose we have a gravitational wave which obeys the equation: $[G_{tt}-c^{2}G_{xx}]h_{\mu\nu}=0$ Lets take the case where $h_{\mu\nu}\ne0$ so we are left with the classical wave equation.Suppose...

0 answers  ·  posted 11mo ago by Volpina‭

66%
+2 −0
Magnetization as a function of temperature in ferromagnets

Suppose a ferromagnetic material with initial magnetization $M_o$.Is there some specific formula which calculates the total magnetization $M$ as a function of $M_{o}$ and the Curie temperature $T_{...

1 answer  ·  posted 1y ago by MissMulan‭  ·  last activity 11mo ago by Anyon‭

50%
+0 −0
What do eigenfunctions and eigenvalues mean physically?

Lets say we have a mass connected to a spring.Assuming not any friction the ODE which describes the system is $m\frac{d^{2}x}{dt^{2}} = -kx$ We can set 2 Dirichlet boundary conditions $x(0)=0$ an...

1 answer  ·  posted 12mo ago by Volpina‭  ·  last activity 12mo ago by Technically Natural‭

75%
+4 −0
What's the meaning of "outdated" in physics?

I was recently reading some questions here and there saying that "relativistic mass is outdated". I saw someone saying that "outdated" doesn't mean the concept is wrong. My question is what physici...

1 answer  ·  posted 2y ago by deleted user  ·  edited 12mo ago by Reinstate Monica on Stack Exchange‭

50%
+0 −0
What is the uncertainty principle and how does it relate to the measurement of particles?

I'm trying to understand the uncertainty principle and its implications for particle measurement. From what I've read, it seems that the principle states that we cannot simultaneously know the exac...

0 answers  ·  posted 1y ago by Reinstate Monica on Stack Exchange‭

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+3 −0
How to find position of a particle at a time given a position dependent force

If we have a force which changes depending on the position of a particle, how can we find the position of the particle at some time $t$? We can find its velocity if it has travelled a given distan...

1 answer  ·  posted 3y ago by MissMulan‭  ·  edited 1y ago by Trilarion‭

60%
+1 −0
Direction of vector of electric field

Suppose we have a arc of charges with some charge density $\lambda(\theta) = sin\theta$.I am using polar coordinates for convenience.But how can I find the direction of the unit vector of the net e...

0 answers  ·  posted 1y ago by MissMulan‭  ·  edited 1y ago by samcarter‭

25%
+0 −4
How can I easily UNcouple this slide and lock, on office chair? [closed]

I need to separate these two parts, the opposite of the GIF below. While my hunky husband was lifting the chair up, and my brawny brother pushing the frame down, I kept hitting the top of the slid...

0 answers  ·  posted 1y ago by Este‭  ·  closed 1y ago by Monica Cellio‭

60%
+1 −0
Maxwell equations EM wave confusion

The general formula for a EM wave (solving for the E field) is: where $\varepsilon = \varepsilon _{r}+j\frac{\sigma }{\omega }$ My professor told me that the conductivity of vacuum is 0 so we...

0 answers  ·  posted 1y ago by MissMulan‭

50%
+0 −0
maxwell equation in 1d

Maxwell's first law in differential form states that $$ \triangledown \cdot E = \frac{\rho}{\epsilon_{o}} $$ . In case of 1d can we say that $$\rho = \lambda$$ where $$\lambda$$ is the linear char...

1 answer  ·  posted 1y ago by MissMulan‭  ·  last activity 1y ago by celtschk‭

28%
+0 −3
Is this a physics discussion or new energy? [closed]

Part 1 Say we have a round water pool, the radius is 10m, and the water depth is 2m. C is a fixed point: Fixed on the surface of water. Fixed at the center of the pool. F1 is stable forc...

2 answers  ·  posted 1y ago by HolyDamn2.0‭  ·  last activity 1y ago by Mithical‭

28%
+0 −3
What are the efficient methods to vacuum or pump air into 15 meters underwater?

Say we have a four underwater components tidal power / hydro power system. Component A. A propeller would always orient along the same direction regardless the direction of the flow. This is th...

0 answers  ·  posted 1y ago by HolyDamn2.0‭  ·  edited 1y ago by HolyDamn2.0‭

75%
+4 −0
If you're stopped and about to be hit from behind, should you brake or release the brake?

The title is a framing for a theoretical question; I'm not asking for practical advice. A friend was recently in this situation and my attempts to apply what I remember of a couple semesters of co...

1 answer  ·  posted 1y ago by Monica Cellio‭  ·  last activity 1y ago by Olin Lathrop‭

71%
+3 −0
How exactly do eddy currents slow down objects moving though a magnetic field

When a pendulum made of a conducting material moves through a magnetic field, it's a well-established fact that it experiences a retarding force, thus slowing it down, however, I'm unable to unders...

1 answer  ·  posted 1y ago by esrdtfghjk‭  ·  last activity 1y ago by Olin Lathrop‭

60%
+1 −0
Double slit experiment with 2 electrons fired from a gun

Suppose we perform the double slit experiment , but we fire instead 2 electrons instead of 1. In the double slit experiment performed in the 1920s a interference pattern was observed at the screen...

0 answers  ·  posted 1y ago by MissMulan‭

33%
+0 −2
Differential equation solution cannot describe what happens in reality

Suppose we have a free falling object inside a planet's gravitational field with strength g.The planet's atmosphere provides a drag force which is dependant from the u^2 of the particle. Suppose t...

0 answers  ·  posted 1y ago by MissMulan‭  ·  edited 1y ago by MissMulan‭

25%
+0 −4
Classical Uncertainty

Suppose we are using a force gauge to measure gravity in a planet. We set the gauge force to the 1N range which has a resolution of .01 N. From its specs the error introduced during the measurmen...

0 answers  ·  posted 2y ago by MissMulan‭

50%
+0 −0
Calculate inductance using laws of electromagnetism

Get 2 conductors and seperate them we can use Gauss's law to calculate the capacitance created by the seperation of the 2 conductors.Can we use other laws of electromagnetism to calculate the induc...

2 answers  ·  posted 2y ago by MissMulan‭  ·  last activity 2y ago by TonyStewart‭

50%
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System of ODEs models in physics

What examples of a system can be described by a system of ordinary differential equations?

1 answer  ·  posted 2y ago by MissMulan‭  ·  last activity 2y ago by Olin Lathrop‭

25%
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How are charges sorted?

Im designing a capacitor and I have decided to make the surface of 1 plate of the capacitor bigger than the other plate. How are the charges sorted through A2?Are they spread out to cover all th...

0 answers  ·  posted 2y ago by MissMulan‭

50%
+0 −0
Meaning of complex frequency [closed]

If we have a LC high pass filter the transfer function H(s) becomes: $$ H(s) = \cfrac{sL}{sL + \cfrac{1}{sC}} $$ If we solve for s to find a pole of the transfer function we get: $$ s = j \cfrac...

0 answers  ·  posted 2y ago by MissMulan‭  ·  closed 2y ago by MissMulan‭

25%
+0 −4
Why can these Single Vision lenses slow myopia for kids, but not adults? [closed]

These WorldFamous companies advertise that their lenses can control myopia for kids, NOT adults. But none of these lenses are approved by FDA. I asked my optometrist why merely kids, not adults. Bu...

1 answer  ·  posted 2y ago by TextKit‭  ·  closed 2y ago by Mithical‭

33%
+0 −2
Optically, why are circular eyeglasses lenses better than rectangular?

My optometrist said that round eyeglass lenses are OPTICALLY better than rectangular, particularly to correct myopia. He was NOT referring to fashion or style. I couldn't understand his explanatio...

1 answer  ·  posted 2y ago by TextKit‭  ·  edited 2y ago by TextKit‭

50%
+0 −0
Time dilation with current or very near technology of the next 100 years

With time dilation a cosmonaut could travel forth in time, especially in light speed. But are there much lesser speeds which might be achievable by humans in the next 100 years which could also in...

0 answers  ·  posted 2y ago by deleted user

33%
+0 −2
Why can someone observe light, even when the light fails to illume that someone?

I never grokked the optics behind LightHouses and the WW2 poster below work. LightHouse beams are narrow and focussed. Doubtless, the light source can fail to illumine a seafarer or the enemy subm...

1 answer  ·  posted 2y ago by TextKit‭  ·  last activity 2y ago by Olin Lathrop‭

28%
+0 −3
Why do markers reflect light, even when the light source fails to illumine the space between the source and markers?

Please see below screenshot of 15:59.The LED spot light (fastened to the front of the boat) illumines merely a few meters in front, and fails to illumine most of the water between the boat and the...

1 answer  ·  posted 2y ago by TextKit‭  ·  last activity 2y ago by Olin Lathrop‭

50%
+1 −1
What's the equation of kinetic energy of charged particle?

I was looking for equation of motion. I came up with a solution but it doesn't satisfy me. Cause I was trying to find motion of that particle using Lagrangian. We know that $$W=\int \vec F\cdot d\...

1 answer  ·  posted 2y ago by deleted user  ·  edited 2y ago by deleted user

50%
+1 −1
Is $E=mc^2$ true for all frame of references?

Which one is correct? $$E=mc^2$$ or $$E^2=(mc^2)^2+(pc)^2$$ I mostly seen $$E=mc^2$$ from my childhood, and when I was learning problem solving in relativistic mechanics I had seen $$E^2=(mc^2)^2...

1 answer  ·  posted 2y ago by deleted user  ·  edited 2y ago by deleted user

71%
+3 −0
What is virtual work?

$$\sum_i F_i \cdot \delta r_i$$ is virtual work when internal force is $0$. For that reason, $$\sum_i F_i \cdot \delta r_i = 0$$ Here internal force stands for what? When a object's displacement ...

1 answer  ·  posted 2y ago by deleted user  ·  last activity 2y ago by deleted user

60%
+1 −0
Calculating Surface temperatures of a thermal insulator

I'm interested in knowing the surface temperature of both sides of a double-pane or triple-pane window. Given the R-value of the window, and the air temps outside and inside, how can I calculate t...

1 answer  ·  posted 2y ago by re89j‭  ·  last activity 2y ago by Olin Lathrop‭

71%
+3 −0
Calculating Max humidity for a house

I want to write some code to control my whole house humidifier. I want my code to calculate the percentile relative humidity above which dew will form on my windows. I have sensors for air tempera...

0 answers  ·  posted 2y ago by re89j‭

40%
+0 −1
Book suggestion on classical thermodynamics

I was looking for book on classical thermodynamics. I found lot of related posts in PSE but couldn't find a book which type I was expecting. I was searching for book which covers the whole thermody...

0 answers  ·  posted 2y ago by deleted user  ·  edited 2y ago by deleted user

60%
+1 −0
Conductivity with angle of light

In the lab I changed the angle the light hits a photoresistor and it doesnt obey Lambert's cosine law the conductivity of the photoresistor drops fast from +-20 to +-30 degrees angle.Why?

1 answer  ·  posted 2y ago by MissMulan‭  ·  last activity 2y ago by Olin Lathrop‭

75%
+4 −0
How are the assumptions behind two ways of deriving the Rayleigh-Jeans law related?

The Rayleigh-Jeans law does a good job of describing the spectral radiance of a black body at low frequencies: $$B_{\nu}(T)=\frac{2kT\nu^2}{c^2}$$ with $T$ the temperature and $\nu$ the frequency...

1 answer  ·  posted 2y ago by HDE 226868‭  ·  last activity 2y ago by Derek Elkins‭

60%
+1 −0
May it be that there are more than 8/9 planets in our solar system?

May it be that there are more than 8/9 planets in our solar system which aren't detectable with the current technologies? Is there any theory suggesting that our solar system has more planets, all...

1 answer  ·  posted 2y ago by deleted user  ·  last activity 2y ago by Canina‭

60%
+1 −0
Is that electron which jumps from one stationary state to another?

In classical physics book of kleppner, i read that An atom can "jump" from one stationary state a to a lower b by emitting radiation with $E_a-E_b$. The frequency of the emitted "package of radi...

1 answer  ·  posted 2y ago by deleted user  ·  last activity 2y ago by Olin Lathrop‭

71%
+3 −0
Why series springs behave like parallel? A comparison between parallel resistance and series spring.

I know that equation for parallel resistance is $$\frac{1}{r_{tot}}=\sum_i \frac{1}{r_i}$$ But i wonder to see equation of series spring constant. If we add multiple spring in series. Then their ...

1 answer  ·  posted 2y ago by deleted user  ·  last activity 2y ago by Olin Lathrop‭

50%
+0 −0
How electric displacement is proportional to surface charge?

$$\begin{alignat}{2} && \vec \nabla \cdot \vec D & = \rho_f \\ & \implies &\int_V \vec{\nabla} \cdot \vec D \mathrm d\tau & = \int_V \rho_f\ \mathrm d \tau \\ & \impl...

1 answer  ·  posted 2y ago by deleted user  ·  last activity 2y ago by deleted user

20%
+0 −6
Are lamps, with blistering light bulbs exposed and facing down on the user, dangersome?

IKEA discontinued this NOVEMBER lamp in 2007, but I still use it. IKEA confirmed that they did not intend or design any cover or share with this lamp, and the light bulb is supposed to be exposed. ...

2 answers  ·  posted 2y ago by TextKit‭  ·  last activity 2y ago by celtschk‭

71%
+3 −0
How can the kinetic energy equation be intuitively understood?

Momentum is proportional to an object's velocity, and kinetic energy is proportional to the square of its velocity $\dfrac{mv^2}{2}$. It's pretty intuitive that if object B is going twice as fast a...

3 answers  ·  posted 2y ago by gmcgath‭  ·  last activity 2y ago by celtschk‭