0
votes
1answer
119 views

Are there any naturally occurring examples of photons without mass?

I read that a photon is said to have zero mass at zero velocity. Does this mean that they only exist in a state of probability until observed && interacting with some system? And then when ...
0
votes
2answers
110 views

Do transformers lose energy?

EDIT: The title should rather be how/why transformers lose energy My idea of a transformer is that it is composed of two separate wire windings around some metal core. The purpose is to ...
0
votes
2answers
69 views

Fractional quantum Hall effect [duplicate]

Can someone explain the fractional quantum Hall effect in layman's terms, I'm having some difficulty understanding it?
0
votes
5answers
543 views

How do magnetic field lines cancel outside of a solenoid?

Please explain me briefly, how magnetic field lines cancel outside solenoid? There is only one wire wrapping it and therefore only one direction of current so how can magnetic field cancel out? How ...
0
votes
2answers
62 views

Field theory for a finite temperature normal fluid

Can normal-fluid (not superfluid) hydrodynamics be derived from some classical field theory? Here I mean conservation (continuity) equations for mass (density), momentum, and energy (entropy, ...
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votes
2answers
82 views

What is the physical reason that the undamped driven oscillator has mean power zero?

The instantaneous power absorbed by an undamped driven oscillator is given by:$$\mathbf{P} =-\omega\dfrac{F_o/m}{{\omega_0}^2 -{\omega}^2} F_0 \sin{\omega t}\cos{\omega t}$$. But my book says the mean ...
0
votes
1answer
102 views

Does nucleus itself has its own motion?

We know that electron(s) is(are) moving around the nucleus, that consists of protons and neutrons. But does nucleus itself has its own motion, its own momentum, or the nucleus is stationary? Now, is ...
0
votes
3answers
122 views

What happens to half of the energy in a circuit with a capacitor?

For a simple circuit with a battery supplying a voltage V to a capacitor, let us assume that the charge on the capacitor is Q. Now, the work done by the battery or the energy supplied is given by the ...
0
votes
2answers
83 views

Why are L4 and L5 Lagrange points stable as points and not part of a circle?

I read this Phys.SE thread which is similar Why are L4 and L5 lagrangian points stable? but I did not want to necro that thread. It seems that most discussions of a three body problem are presented ...
0
votes
2answers
504 views

Work done by moving up an inclined plane

Suppose an object is pushed up a smooth inclined plane from ground level to a point h above the ground with force F. The angle of inclination is A. How much work is done? To push an object up a ...
0
votes
2answers
51 views

How to determine whether a nuclear transition would be electric octupole, or hexadecapole?

The transition from one nuclear state to another is classified as quadrupole/octupole, etc, depending on the units on angular momentum transferred. But depending on the angular momentum of the two ...
0
votes
1answer
1k views

Application of Coulomb's Law

I've just finished reading a section in a book on Coulomb's Law. I'm trying to practice the math a bit and came up with the following: Suppose you have two charges, -5uC ($q_1$) and 7nC ($q_2$). ...
0
votes
1answer
83 views

Why mirrors form image and others don't?

In the case of mirror, I understand how a image is formed, If I replace plane mirror by wood or some other opaque material in the above image and position of object(bottle) and eye remain the same , ...
0
votes
2answers
83 views

How to determine which object is moving relativistically?

Apologies in advance if I've overlooked some obvious point. In relativity, I know that there is no way to know if Object A or Object B is moving relative to the other. Each would see themselves as ...
0
votes
2answers
311 views

Hot air ballon and a sandbag moving at constant velocity

Suppose you are in a hot air balloon with a sandbag that has a certain mass. The hot air balloon is moving upwards at a constant velocity of $15$ $m$.$s^{-1}$. If you throw the sandbag out of the hot ...
0
votes
1answer
89 views

EM waves in conductors

On a recent test in my E&M class, we derived what happens to an EM wave propogating in a conductor of conductivity $\sigma$, but I'm having trouble understanding the results. We started from the ...
0
votes
1answer
336 views

About a recent experiment which claims reality doesn't exist until we measure it?

Reality doesn't exist until we measure it, Quantum Experiment confirms. Is this one more experiment which is the victim of how news generally hypes stuff like this? This is a section from the ...
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votes
2answers
574 views

Is a string taut if the tension is zero?

I'm studying vertical circles and a particle on a string will remain in motion as long as the string is taut. However, what if there is 0 tension in the string? Is it still technically taut?
0
votes
1answer
103 views

Is sunlight like a spotlight? [closed]

It is believed that if earth would have no atmosphere then the sunlight would fall on earth like a spot light. According to this fact the sunlight on moon must fall like a spot light. Does it? Then ...
0
votes
1answer
40 views

Notation for $N$-particle wave functions

If we have one particle we first look at an orthonormal basis of the one-particle Hilbert space $|n\rangle$. Here $n$ is the abbreviation for a compete set of quantum numbers, for example $n = ...
0
votes
2answers
108 views

Why does the ball lose contact if it has velocity great or less than $\sqrt{rg}$, while moving over a smooth sphere of radius $r$?

Let a ball of mass $m$ is given a velocity over the the top of a smooth sphere of radius $r$. The equation of motion at the topmost point will be $$mg - N = m\dfrac{v^2}{r}.$$ As $v$ increases, $N$ ...
0
votes
1answer
39 views

When align the neutron's magnetic dipole moment, does moving neutron radiates?

Was performed an experiment in the past, where neutrons pass a magnetic field and their magnetic dipole moment get aligned? Was measured an electromagnetic radiation during the experiment?
0
votes
1answer
70 views

Is a zero-energy universe necessarily also a zero-information universe?

The universe needs to be near zero energy to not crumple in on itself. Under the same logic, does it also need to have near zero information content to prevent the passage of time from burning it to ...
0
votes
2answers
112 views

Lorentz force Law

I want to ask a fundamental question about Lorentz force equation. Why is it important to incorporate both electric and magnetic forces into one single expression? I know magnetism is electricity's ...
0
votes
1answer
84 views

Can someone explain what's the difference between all these terms in “Simple Words” with their “applications”? [closed]

I'm very confused between all these terms. Can someone explain what's the difference between Classical Mechanics, Relativistic Mechanics, Quantum Mechanics, Quantum Field Theory, ...
0
votes
4answers
218 views

Ohmic Heating in Wires

please could someone tell me why Ohmic losses are always referred to as $I^2 R$ losses? Here is my problem. If the power coming from a power station is fixed then you can either deliver this power as ...
0
votes
1answer
27 views

Adjoints in occupation number representation

I am having some trouble understanding how to compute things in occupation number representation. I believe my problem is only implicitly dealt with in the notes I have read. A simple example should ...
0
votes
4answers
931 views
0
votes
1answer
118 views

What physical properties can we measure most accurately?

As far as I am aware, frequency is the most accurate physical property we can currently measure. This has led us to very high standards of experimental verification of e.g QED predictions and the CMB ...
0
votes
3answers
264 views

How exactly does wave theory of light fail to explain blackbody radiation? [duplicate]

I don't really understand the reason why wave theory of light fails to explain the blackbody radiation. My textbook says the Planck's quantum theory explains blackbody radiation. It says "If we ...
0
votes
2answers
61 views

It's All About Earthquake! [closed]

All the following informations i've got are from a book.(i want to check that whether the informations are correct or not,that book isnt a science book though) There is a limit to which earth can ...
0
votes
1answer
37 views

What is meant by “method of approximate numerical method” or “method of digital computer” for solving the differential equation of resistive force?

I was reading "motion against resistive forces" in Newtonian Mechanics by A.P. French; here is the excerpt: [...] In general, the resistive force $\mathbf{R}$ is is a function of speed, so that ...
0
votes
1answer
51 views

Quantum Entanglement Particle Properties

I have background in static/dynamic/thermodynamic physic. I am reading on quantum physics and quantum entanglement. Me and some of my colleagues were wondering on the properties that are shared ...
0
votes
3answers
183 views

Question on normal force and static friction [closed]

Why is this statement false: If the normal force on an object increases, the static friction must increase? Thank you! Is it because they did not state what normal force is referring to?
0
votes
1answer
51 views

Is it possible to create helium atoms by bombarding heavy water with neutrons?

If heavy water is bombarded by neutrons is it possible that any of the deuterium atoms can capture neutrons and transmute to helium atoms? I suspect the more probable event would be knocking protons ...
0
votes
2answers
179 views

Dimensional Analysis Question [closed]

First of, I would like to say that I have tried this question, and have my answer as well, just not sure such a method of obtaining the answer is valid or not, therefore trying to look for help here. ...
0
votes
1answer
129 views

Helium balloon stays on the floor

So yesterday I came back home with a buoyant helium balloon (no comment, and before you ask, it's blue) and I left it in the house. Obviously, it rose to the ceiling. This morning I woke up to a ...
0
votes
2answers
1k views

Calculating the energy supplied by a battery

If you wanted to calculate the energy supplied by a battery in time $t$ you would use $E=VIt$ where $I$ is the current through the battery. If the internal resistance is $r$ we could also use ...
0
votes
2answers
88 views

Frames of reference and why are they different

Here is a quote from "The Elegant Universe" by Brian Greene. Imagine two countries that have been at war are sitting down to sign a treaty ending hostilities while traveling aboard a train that is ...
0
votes
1answer
566 views

Question about ohmic conductors

I'm having some trouble understanding Ohm's law. My trouble is with the different ways it is described when referring to ohmic and non-ohmic conductors. If someone can answer this question I think it ...
0
votes
3answers
147 views

Is it possible that the charged sphere can lose mass by adding electron?

While studying Electrostatics, I was wondering about whether a charged sphere gains or loses mass while just adding electrons? If it is possible then the negatively charged sphere will have more mass ...
0
votes
1answer
65 views

Why water expands when freezes? [duplicate]

I'm sure this is for most of you a basic question, but it really puzzles me: How it is that, even though all materials expand as they get warmer, and contract (maybe these are not the correct terms) ...
0
votes
1answer
373 views

Pendulum on the moon, (Highschool)

A simple pendulum used as a clock, set with the correct time at earth, was sent to moon, it was noticed that it is late 36mins for each hour on earth. Calculate the ratio between acceleration of ...
0
votes
2answers
90 views

Energy transitions of 12.1eV electron?

Here is part of the energy level diagram of hydrogen: n=4 --> -0.85eV n=3 --> -1.50eV n=2 --> -3.40eV n=1 --> -13.6eV When an electron of energy 12.1eV collides with this ...
0
votes
3answers
172 views

Since the gravitational force is only attractive, why does matter not just concentrate into a small sphere?

This doubt has been wandering in my head for a long time. The gravitational force is only attractive force not a repulsive force. Since gravitational force is only attractive force, why not the ...
0
votes
1answer
58 views

is it necessarily true that the partition function $Z$ (with degeneracies) $ =1$?

The partition function with degnerate energies is $$\text{Z}=\sum _ig_ie^{{-E_i}/{k_BT}}.$$ Because the partition function Z is defined as the normalisation constant, does Z always = 1?
0
votes
2answers
619 views

Will going up with a larger diameter ensure a higher water pressure in the distribution pipes? [closed]

Have a look at the drawing below describing a sample situation: a water tank a 1'' diameter pipe bringing the water down, inside the ground, arriving near the house in the house, 2 x 0.5'' diameter ...
0
votes
2answers
134 views

Charging a capacitor using a capacitor?

I recently did an experiment using a fully charged capacitor (assumed) and charged a separate capacitor through fixed resistor. We measured the potential difference of the capacitor being charged. We ...
0
votes
3answers
118 views

What triggers a nuclear chain reaction?

A nuclear fission works by spliting atom's neutrons by neutrons which release energy but how is the chain reaction triggered because at first the nucleus is bond by a strong nuclear force so what ...
0
votes
1answer
324 views

Fleming's left hand rule

in Fleming's left hand rule is the direction of current showing the direction of the flow of electrons or the direction of positive charge?

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