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If A $\rightarrow$ B+C+ΔE, then
$M_{B}+M_{C}< M_{A}$ So, whether the masses involved were the relativistic or the rest, they aren't conserved. So, why would anyone say the rest masses, not the relativistic masses, are the ones that transform into energy, how to determine which is which?
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If we have a Lagrangian with a global internal symmetry $G$. Why do the conserved currents transform under the adjoint representation of $G$? Is it a general statement (if this is the case, how can we derive it?), or does it depend on the representation of the fields in the Lagrangian?
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I want to perform quantum state tomography. For that, I need to construct a production spin density matrix $R$ . But I am unable to write it. I can write the matrix element for the process eg. $\tau^+ \tau^-$ going to $e^+ e^-$, but I am unsure how to proceed. Is there any example that explicitly shows the calculation ... |
I'm writing a research paper exploring how damping ratio of a simple pendulum relates on its initial angular displacement.
In order to validate the findings of my paper, I am required to include a comparison to the findings of past research papers, or to a theoretical model derived from an equation connecting initial a... |
I want to calculate the Keplerian orbital elements in the central force case.
Given the mass M of the "sun" in kg, the eccentricity $e$ of the orbit, and the period $T$ in seconds, I believe that is sufficient to calculate the rest of the parameters (provided we make assumptions of convenience, e.g. $\theta=0$ at $t=0$... |
Can I get use a superconductor as a ‘shield’ to ‘focus’ the magnetic field analogous to water flow out of a pipe?
If yes then I could get a perendev magnet motor to work?
If not then why not?
As I understand it, the one variation of the prendev motor used a ferromagnetic shield.
This question relates to repeating it wi... |
Consider a bottle
filled with water,
with an air tight lid,
with a hole at height h.
It's well known that the water doesn't flow out when the lid is closed.
Now, if a straw is inserted through the lid, while maintaining air tightness,
water flows out if and only if the bottom end of the straw is higher than the hole.
A... |
I recently learned that $\vec{v} = \vec\omega \times \vec{r}$.
$\vec\omega$ being the angular velocity vector of a particle, $\vec{r}$ being its position vector, and $\vec{v}$ being the linear velocity vector.
Let's suppose the particle is currently rotating around the Z axis.
We can always say: $\vec\omega = \vec\ome... |
During phase change, latent heat is responsible for change in internal change and also for work done by or on system as it's volume increases or decreases. But how do we calculate the work done by system. For example:
When 1 g of water at 0°C and 10^5 N/m² pressure is converted into ice of volume 1.091 cm³, find the wo... |
I may misinterpret the question. In the lecture note of conformal field theory, arXiv:2207.09474, it says the following
where for $P^\mu=i\partial_\mu$ and $D=ix^\mu \partial_\mu$. I am confused whether we can say anything about the dimension of $P^\mu$ or $K^\mu$ solely from the commutation
$$
[D,P^\mu]=-iP^\mu\; \te... |
I am reading through the derivation of the Boltzmann transport equation in the text, Statistical Mechanics of Particles by Kardar. I am unable to make sense of the conservation equations described.
There are two particles, before a collision at $\vec{p}_{1}$, $\vec{p}_{2}$. After collision, they transform $\vec{p'}_{1}... |
Based on the black hole mass, giving that lower mass black holes have higher mass densities than higher mass black holes.
Energy Densities
`The density is dependent only upon the mass of the black hole,
ρ≈1.85×1019 1/m2
where now $m$ is the mass of the black hole in solar masses i.e. units where 1
means the same mass a... |
If one solves Einstein's field equations for the metric of polytropic gas sphere, one stets the gas density at the surface to zero. However, such condition describes vacuum where both pressure and energy density are zero. At the star's surface I expect a non-zero energy density due to the presence of gas molecules ther... |
I've found this question impossible to find online because all the answers talk about the boiling points and freezing points at different altitudes.
The question is whether the rate of cooling or heating changes with altitude. So, practically speaking, if the boiling point is 90 C because I am at elevation, it takes x ... |
Before this i will actually give a question which i was able to solve and here is the quesiton
The answer is obviously (4) and since i do not know differentiation is solved it as follows
This was quite a way to solve the question without differentiation, however have a look at the following question
When i tried to ... |
I know the formula for angular momentum about the axis of rotation i.e, $L = I\omega$. But what if I need to calculate the angular momentum about some axis other than the axis of rotation. Is it going to be the same as $L$ about rotational axis or is it a different value?
|
I would be extremely grateful for any help that anyone could offer here.
I am interested in solving the optical bloch equations for the excited state population Rabi oscillations with damping due to spontaneous decay. The problem that I have is not solving the equations mathematically, but making sense of the units.
Es... |
I'm struggling with some basic intuition regarding the angular velocity $\vec\omega$ and angular momentum $\vec{L}$ vectors, for any arbitrary motion. Specifically, I'm trying to figure out what the idea is behind their directions. (The idea behind the magnitudes is more clear).
First I'll explain what (I think) I know... |
I am a mathematician and know nothing about physics, although I am trying to solve a problem related to physics. If someone could help or provide some suggestions, I would be grateful.
I have a speedy boat navigating in the sea. The boat could be very small and not so heavy. Some breeze blows, and there exists a curren... |
It seems to me that HVT (hidden variables theories) were first imagined as a way to escape intrinsic randomness of QM (by this I mean unpredictability, or one-to-many property : one initial condition give many possible results; one being selected randomly for every experiment).
But this seems impossible from the start,... |
The total force on a charge is equal to $\mathbf {F}=q\mathbf {(E+ v×B)}$ where everything have their usual meanings . We can say that:
$$dW= \mathbf {F\cdot dl} = {\mathbf{F}\cdot \frac{d \mathbf{l} }{dt}} dt= \mathbf {(F\cdot v)}dt = q(\mathbf {E\cdot v})dt = \mathbf {(E\cdot j)} dt ...... $$
where $\mathbf {j}$ is ... |
The question regarding which i am asking this question is as follows
In an experiment for determination of the focal length of a thin convex lens, the distance of the object from the lens is $10 \pm 0.1cm$ and the distance of its real image from the lens is $20 \pm 0.2cm$. The error in the determination of focal lengt... |
I've been studying the Polyakov action and Virasoro constraints in string theory, and I've come across their specific forms in 2 dimensions (2D):
$$S = -\frac{1}{2} \int d^2 \sigma \sqrt{-det(G_{\alpha \beta})} e^{-2s}$$
$$L_n = \frac{1}{2} \int d^2 \sigma \left( \partial_\alpha X^i \partial^\alpha X^i - n \right) e^{-... |
Why do charges exist, how did they come into existence? (if any theories exist, then please explain them in somewhat detail)
What would happen if charges never existed?
Please explain the answers at the scope of an 11th standard student
Thank you
|
Consider angle = $x^ \circ$. Then according to a free-body diagram
$$mg=2T\text{cos}x$$ and
$$T=\frac {mg}{2\text{cos}x}$$
So I know $x$ is mostly $0^ \circ$. But what about at $180^ \circ$? Is it still minimum? At what angle between your arms would you experience minimum tension while hanging from a bar? Would tensio... |
This is a trick question but it leads up to the real question. Let me explain.
The Doppler effect for sound is not symmetric. For a given relative velocity between source and receiver, the measured Doppler shift is different depending upon whether it is the source that is moving, or the receiver. This can be seen from ... |
Consider two copies of a general pure two-mode Fock state with a definite number of photons $N$ as follows.
$|\psi\rangle^{\mathrm{TMFS}}=\sum_{n=0}^{N} c_{n}|n\rangle_{a}|N-n\rangle_{b}$ where $c_n$ are generic coefficients and $a$, $b$ are the two modes. Some specific states that fall under this class of states are t... |
I'm trying to create a YouTube educational science video on Quantum Field Theory and the Standard Model. I'm not a physicist (just a hobby), and would love feedback on my explanation below, and help to point out (or rewrite) parts that are scientifically inacurate or misleading. Or just point me to literature.
"But som... |
In this study, the authors provide an equation for operating cell voltage: $V_{cell} = V_{rev} + V_{act} + V_{ohm}$, the sum of the reversible overvoltage, the activation overvoltage and the ohmic overvoltage of electrolyte. The authors define $V_{act} := s\log\left(\frac{t_1 + \frac{t_2}{T} + \frac{t_3}{T^2}}{A}I + 1 ... |
Reflection coefficient from the scattering approach in tortoise coordinates, looks exactly like relationship between modulus squared of Bogoliubov coefficients. However I'm not able to figure out a way to connect these two approaches.
Could someone please explain this or point me to an article, a paper or a book which ... |
I know that for an isothermal process heat transfer is necessary so process should be slow and walls should be conducting for heat transfer to occur as a process cannot be isothermal and adiabatic at same time. But why slow compression of piston need to be isothermal, can't it be neither isothermal not adiabatic?
For e... |
I have been looking into the derivation of the Maxwell speed distribution function as for instance given in https://en.wikipedia.org/wiki/Maxwell%E2%80%93Boltzmann_distribution#Distribution_for_the_speed or elsewhere.
In all these treatments it is claimed that the velocity distribution functions in the $v_x, v_y, v_z$ ... |
I understand that when a photon is absorbed or when an electron collides with an atom the electrons may gain energy and become excited if the energy corresponds to a difference in energy levels. In the gold foil experiment the zinc sulphide screen produced a flash of light when the alpha particles hit it. What I’m conf... |
In the classical (typically large occupation number) limit of QFT, the dynamics of, say, a scalar field can be approximated by its classical field equation. Let's consider the Klein-Gordon equation:
$$
0 = \ddot\phi - \nabla^2\phi + m^2\phi.
$$
One can then relate the field bilinear $\phi^2$ to the occupation number: i... |
I current am working a 2d physics engine, but have recently hit some bumps in the road.
Polygon to polygon collision and velocity resolution works without issue, but I am struggling to get working circle to circle and circle to polygon angular velocity resolution working as expected.
Each circle has 5 values related to... |
In Stein & Shakarchi's Fourier Analysis, the Fourier transform of a Schwartz function $\psi$ is defined to be
$$\hat{\psi}(\xi) = \int_{-\infty}^\infty \psi(x) e^{-2\pi i x \xi} dx$$
which gives the uncertainty principle as
$$\Big(\int_{-\infty}^\infty (x-\overline{x})^2|\psi(x)|^2 dx\Big)\Big(\int_{-\infty}^\infty (\x... |
I'm trying to understand how magnetic monopoles and how its potential mirror and antiparticle counterparts would behave. So according to the modified lorentz force law
$$\vec{F}=q_e\left(\vec{E}+\frac{\vec{v}}{c} \times \vec{B}\right)+q_m\left(\vec{B}-\frac{\vec{v}}{c} \times \vec{E}\right)$$
Say a moving magnetic mono... |
This is a follow-up question after this one:
Yes, the curvature is enough to bend lasers. In fact, there is an interesting feature in Schwarzschild spacetime that might answer your question well. but in principle you can arrange light to orbit the black hole indefinitely.
I should add that this does not necessarily m... |
Last night I was thinking about the AdS/CFT correspondence, and I thought of the following scenario:
Consider a 4D AdS universe with only a single black hole. Assuming the bulk and boundary are perfectly dual, then we expect just a single black hole on the 3D boundary right? But if we invoke the holographic principle t... |
I was hoping someone can help me understand the math behind the electric field (electrostatics). I have gaps in my knowledge about integrals and derivatives (university moves very quickly and it has been years since high school) so I'm hoping someone can help me intuitively understand the math so I know how and when to... |
The question is as follows
In an experiment for determination of the focal length of a thin convex lens, the distance of the object from the lens is 10 ± 0.1 cm and the distance of its real image from the lens is 20 ± 0.2 cm. The error in the determination of focal length of the lens is n%. The value of n is _______.
... |
This question is motivated by a perceived incompleteness in the responses to this question, which asks why we can't just substitute $\dot{q}(p)$ into $L(q,\dot{q})$ to convert it to $L(q,p)$, which seems simpler than the method of using the Legendre Transform to generate the Hamiltonian. Some of the answers correctly s... |
As seen here, there are two T-38's going supersonic. What happens when those shockwaves interact? They seem to dissipate in some places on this photo when they interact. Any source online says that they will "produce complex patterns of compression, rarefaction, and reflection."
However I can't find anything on why th... |
How do I derive the formula of frequency of a organ pipe for a standing wave? When both ends are closed assume there are diaphragm at the end, which are producing the wave.
|
In optics, we usually consider a non-magnetic medium where the magnetization $M$ is zero, while the polarization P is proportional to the electric field $P=\epsilon_0\chi E$. $P$ is induced by some microscopic dipoles with dipole moment $p$. These dipoles would align with the electric field's direction. I wonder if it ... |
Context: My physics friend told me that heating and cooling effects are identical if you flip the vertical coordinates accordingly. If you heat a room from below, the warm air rises. Identically, air sinks if you cool the ceiling (which is like heating if you are looking at it upside down).
Problem: I don't have a good... |
In Gauge/Gravity Duality by Ammon and Erdmenger (pg. 105), and CFT Lecture Notes by Osborn (pg. 4), it is stated that the interval between two points $x$ and $y$ transforms under general conformal transformation as:
$$
(x' - y')^2 = \frac{(x - y)^2}{\Omega(x) \Omega(y)}
$$
Where $\Omega(x)$ is a point-by-point scaling ... |
So I was reading this Landau and Lifshitz paper:
https://doi.org/10.1016/B978-0-08-036364-6.50008-9
The article can also be found without a paywall by just searching its title, "On the Theory of the Dispersion of Magnetic Permeability in Ferromagnetic Bodies".
At page 19 (page 6 of my pdf), they have to solve a rather ... |
I'm reading a book on physics in which there is a line that I do not understand.
I quote it here:
If a body is placed on a horizontal surface, the
torque of the contact forces about the centre of mass
should be zero to maintain the equilibrium. This may
happen only if the vertical line through the centre of
mass cuts ... |
In its simplest version, it states that
the effects of a uniform gravitational field are indistinguishable from those of a uniform linear acceleration of the frame of reference
The thing is, you can peacefully stand on the surface of the Earth for a year (or more), but you can’t accelerate uniformly at $9.8 m/s^2$ fo... |
why is a constant force and constant linear speed requirements for uniform circular motion? I think I understand the idea of constant force:
this is what comes to mind when I think of force changing but would like to confirm that that's the reason. However I do not understand why linear speed/angular speed have to be ... |
I am currently reading Collins's Renormalization: An Introduction to Renormalization, the Renormalization Group and the Operator-Product Expansion, and have reached Chapter 12. However, I am puzzled by the application of Eq. (12.2.14). If I understand correctly, Collins aims to prove that $\langle0|T\delta_R\psi(x)\bar... |
Is there a reference that is considered authoritative when it comes to astronomical data, especially for the planets and their satellites and the Sun?
I've been using the most recent CRC Handbook of Chemistry and Physics and Lang's Astrophysical Data: Planets and Stars (the latter being somewhat old, published in 1992)... |
I need to have a fully functioning understanding of entropy so I've got a few questions to ask
What are the conditions for an increase in entropy to be reversible?
I (think) I know that any process where the temperature is constant is assumed to be reversible, but what other constraints can I put on other thermodynam... |
In the context of formation of large-scale structures, there would be a turnaround radius where expanding matter would detach from the Hubble flow and start to collapse (https://www.aanda.org/articles/aa/full_html/2020/07/aa37337-19/aa37337-19.html)
However, as I understand it, the turnaround radius is related to the m... |
How to find the determinant of $\partial_{\lambda} \delta x^{\mu} $ where $\partial_{\lambda}$ is the four derivative and $ \delta x^{\mu}$ is the del variation in $x^{\mu}$.
The answer is $\partial_{\mu} (\delta x^{\mu})$.
|
I read that the duration of one ultra-short laser pulse in a pulse train can be measured with autocorrelators or more sophisticated methods like Frequency-Resolved Optical Gating (FROG).
In principle one could simply measure the spectral width using a spectrometer and correlate it to the time width of the single pulse.... |
This question is related to my previous one.
The entire linear theory of waves is built on dispersion relations, which represent the algebraic dependence of frequency on wave number. That is we decompose a complex wave motion (Fourier expansion is most often used) into simple harmonic sine waves, and look at the depend... |
I am wondering if anybody has ever calculated the odds of a rogue planet, which has been traveling through interstellar space and then enters into a galaxy, being able to travel all the way to the massive black hole at the center of that galaxy.
I would think that the odds of a rogue planet reaching the black hole at t... |
I am reading Blundell's book of Magnetism in Condensed Matter, and I couldn't convince myself why a $\mu_0$ term pops out in the potential energy expression in Stoner ferromagnetism, i.e. spontaneously spin-split bands, explanation. Below you can see the screenshot of the page that bothers me:
To give more detail, I b... |
Take an observer, who is receiving an electromagnetic wave signal, which is constantly changing. It can be for example from a source of light falling into a black hole, so the observed wavelength is increasing all the time.
The only definition I know is that the wavelength is the distance over which the wave's shape re... |
In this study, (Hidden Fractals in the Dynamics of the Compound Double Pendulum) the authors provide various fliptime fractals (of a double pendulum) for different length combinations. However, when I tried to replicate their results, the shapes (for $3l_1 = l_2$ in particular) did not match up. I used a fourth order R... |
As an interesting exercise, I was wondering whether we could reformulate classical mechanics in such a way that we could use the same mathematical paradigm we use in quantum mechanics. I'll expose it here since I want to know whether this procedure is of any interest, or if it is correct.
For simplicity, I chose a clas... |
Let me start by asking why we need a Poisson bracket like structure on the Hamiltonian phase space? Say we have a constraint, why do we go through the trouble of defining a Dirac bracket structure on the phase space (which is a projection of PB structure) when we can just solve the EOM in normal algebraic terms and mov... |
There are many questions exploring variations upon the Twin Paradox, but none I have seen seem to resolve this thought experiment.
It is often said that the 1g force we feel on earth due to the surface pushing us in the opposite direction of gravity's pull is indistinguishable from a 1g force applied by a spaceship, an... |
I'm a glassblower and I need to test glass formulas for compatibility. I'd like to use a polarimeter as it allows not only the detection of strain, but also informs if a glass needs to be softer or harder. I purchased a Strainoptics A100 analyzer (Senarmont polarimeter) from a surplus supplier overseas. When it arrived... |
I have a question regarding problems that require us to find time period of an oscillating setup that performs SHM. The question is as follows-
The pulley shown in figure below has a moment of inertia I about its axis and mass m. Find the time period of vertical oscillation of its center of mass. The spring has spring ... |
I am trying to calculate the spin susceptibility of BCS superconductors at finite temperatures. It's well known that for conventional superconductors, the transverse NMR relaxation $1/T_1$ exhibits a coherent peak just below the transition temperature $T_c$, while is exponentially surpressed as $e^{-\Delta(0)/T}$ at qu... |
The image below shows the Fermi level shift of the PN junction when the potential of the N region is positive with respect to the P region. My textbook (Semiconductor physics and devices by Donald A. Neamen, 4th edition) states that the Fermi energy in the N region is lower than that of the P region. How does this mak... |
When a single photon is reflected is the same one, or is it a new photon (emitted) while the 'original' photon has been absorbed?
I'm not sure how to imagine a refleced photon - it's not a ball bouncing of the wall I guess (photon bouncing to an electron or nucleus)
But on the other hand I'm not sure how the emitted ph... |
I believe the answer is no, and I will explain my perspective. I would specifically like for answers to address the flaws or merits in the reasoning I present, rather than name call or invoke "I said so" arguments to authority.
I will reference this diagram:
Assume two objects, one hotter than the other, near each oth... |
I want to compare plane and parabolic mirror for collection of photon from a point source. Intuitively, parabolic mirror focuses all rays from point source and gives parallel rays therefore has a higher collection efficiency. How do I mathematically prove it? Can someone help in estimating solid angle for both the case... |
For reference: Does Thermal Radiation From A Colder Object Get Absorbed By A Hotter Object?
Closed by moderators for questioning climate science obliquely.
In textbooks throughout the 20th century, the use of Q = σ(T4b−T4g) as a derivation of the S-B Law applied to heat transfer between objects was qualified by a clear... |
From my understanding energy and matter are interchangeable ($E=mc^2$). Also, motion requires energy, but energy does not require motion.
Now, for my question, as an example, I will use the chain of creating sound with vocal cords.
Does the energy begin with the lungs then they move and transfer energy through the air ... |
Three rods are joined to form a 45–45–90 triangle, which is placed at rest in the x′ y′ plane with its hypotenuse along the x′ axis. O′ moves away from O in the x direction at a speed of 0.92c. What are the angles of the triangle according to O?
I know that observer O, relative to whom O' is in motion, measures a sho... |
For the past few days I have been busy with studying cosmology more specifically chapter 8 in the book by dodelson on modern cosmology. I have the following question concerning equation (8.70) which is the following
$$k_{eq} = a_{eq}H(a_{eq}) = \sqrt{2\Omega_m}H_0a_{eq}^{1/2},$$
where the subscript eq stand for matter-... |
I am to start university soon but can't seem to wait, I looked through some lecture notes for 1st year content and have not been able to find anything that goes through exactly what I need, I am wondering if any of you could direct me to something which goes through all the mathematical concepts like 4x4 matrices etc s... |
For the past few days I've been studying cosmology using Dodelson's book. I am now busy with chapter 8 and was making some exercises. However I got stuck with exercise 8.6 (2nd edition) which goes as follows: We define $a_H(k)$ to be the scale factor at which the wavenumber $k$ equals the comoving Hubble radius, so $k ... |
I don't know how to do this. I need a really good explanation that shows how to get the answer.
Question: An Earth satellite’s orbit is at a 45 degree inclination. It has a perigee altitude of 400 kilometers and an apogee altitude of 2000 kilometers. It has a specific angular momentum of $54,653.38 \, \rm{km^2/s}$. Wha... |
A planet has a mean orbital radius of 5.2 Astronomical Units (AU). What is its period?
how do we find it period using the Kepler’s Third Law.
|
How does light going through a medium make light refract? Here’s a good picture :
The problem with this analogy is it depends on the students or light being connected to each other and as far as I know, parallel photons are not connected to each other. For example if there was a single student, they could slow down an... |
When deriving the ambipolar transport equations for an extrinsic semiconductor under low injection, I have found certain discrepances between different references.
For instance, in Neamen's Semiconductor Physics and Devices (see section 6.3.2 for reference), he constructs said equations from the continuity equations, b... |
In chapter 14 of Jackson the energy radiated per unit frequency interval per unit solid angle is given:
Integration over the angles gives:
Finally, dividing by $\hbar \omega$ equation (14.91) gives the number of photons per unit frequency interval:
Can someone detail the steps Jackson does to go from (14.91) to (14.... |
All items in the universe can be said to have a De Broglie wavelength which is significant if that wavelength is comparable to the object's size (I don't have to worry about my wavelength diffracting me when I walk through a doorway). What is the general upper limit of size for appreciable diffraction/interference in p... |
The question in whose context i am asking this question is as follows
In an experiment for determination of the focal length of a thin convex lens, the distance of the object from the lens is $10 \pm 0.1\hspace{1mm}cm$ and the distance of its real image from the lens is $20 \pm 0.2\hspace{1mm}cm$. The error in determi... |
How are shockwaves able to refract? As said here,
When two shock waves collide, they interact with each other and produce complex patterns of compression, rarefaction, and reflection. The resulting behavior depends on the strength, speed, and direction of the shock waves, as well as the properties of the medium they a... |
According to the content of the following paper
On the relation between entropy and energy versions of thermodynamic
length
The second derivative matrix $D^2 U$ of the internal energy may be used to define a Riemannian structure on the set of
equilibrium states of a thermodynamic system，it was developed by Weinhold.
Ru... |
I don't really get what's the difference between them. What does each thing physically and mathematically signify?
Aren't both things just a dot product with the del operator?
|
Considering the high energy demands of AI training, which can reach several megawatts, I'm curious about the idea of sourcing this energy directly from space, particularly from near the Sun.
Take, for example, the Parker Solar Probe. It orbits about 4 million miles from the Sun, where it's exposed to much stronger sunl... |
The charge of an atom is the sum of its nuclear charges (protons and electrons). If a atom is neutral, does it mean it does not have an net electric field?
I thought about this a lot, here is some of what I found. I am not sure what the right answer is because of conflicting information I found on the internet.
In an H... |
In Dodelson's Modern Cosmology on p. 67 under Neutron Abundance section, he calculates
$$H(x=1) = \sqrt{\frac{4\pi^3GQ^4}{45}}\sqrt{10.75} = 1.13\ \mathrm{s^{-1}}$$
where $x=\frac{Q}{T}$, and $T$ is temperature. Now with $Q= m_n-m_p=1.293\ \mathrm{MeV}$ and converting it to Joules, I am not able to get this value. Plea... |
Suppose a capacitor of capacitance $C$, a coil of inductance $L$, a resistor of resistance $R$ and a lamp are placed in series with an alternating voltage $V$. Now, Its frequency $f$ is varied from a low to a high value while the magnitude of $V$ is kept constant.
Why and how the brightness of the lamp varies? Capacito... |
I'm a first-semester physics student who was recently on a train. On a screen, it said the instantaneous velocity of the train was 176 km / h. We had 4 min left until our destination. I wanted to calculate the distance based on these facts, so I tried using the kinematic equations. More specifically, this one: $X_f = X... |
A film of soap solution of surface tensions $ \sigma$ is made in a cirular wire frame of radius r, two diametrically opposite points A and B of which are connected by a thin and light elastic chord of Young's Modulus Y and area of cross section S. If the film on one side of the chord is punctured, find elongation in t... |
I've read that an increase in $10\, \mathrm{dB}$ results in a doubling of the perceived loudness.
Given that, is my table below correct?
dB
perceived loudness
130
8192
120
4096
110
2048
100
1024
90
512
80
256
70
128
60
64
50
32
40
16
30
8
20
4
10
2
1
1
|
Which orbital of sub-shells $s$, $p$, $d$ and $f$ have Magnetic Orbital Quantum Number $m_l=0$. Like in p sub-shell, which orbital from $p_x, p_y, p_z$ will have $m_l$ as Zero?
Also, how to determine the $m_l$ for any orbital?
|
I have some confusion about how to raise the indices of the Kronecker delta.
To raise and lower indices we use the metric tensor, let's suppose to use the metric (+---).
I should have that $$g_{\mu\nu}g^{\nu\alpha} = \delta_{\mu}^{\ \alpha}.$$
This implies that for example $$\delta_{1}^{\ 1}=g_{1\nu}g^{\nu1} = g_{11}g^... |
I am currently reading Gravitation by Misner, Thorne, and Wheeler (MTW). In the very first chapter on weightlessness they make the following claim:
“Contemplate the interior of a spaceship and a key, penny, nut and pea by accident or design set free inside. Shielded from all view of the world outside by the walls of t... |
In the scheme of covariant quantization of the electromagnetic field, it is assumed that the polarization four-vectors satisfy the orthonormality relation (QFT by Mandl & Shaw): $$\sum_r \varepsilon_{r\mu}(\vec k)\varepsilon^\mu_s(\vec k)=-\zeta_r\delta_{rs}$$ where $$\zeta_0=-1, \zeta_1=\zeta_2=\zeta_3=1.$$ I do not u... |
I'm analyzing an ideal reheat Rankine cycle for a steam power plant operating between the pressure limits of 10 MPa and 10 kPa. The mass flow rate of steam through the cycle is 15 kg/s, and steam enters both the high-pressure (HP) and low-pressure (LP) turbines at 500°C.
I want to determine the total heat input in the ... |
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