Law Definition and 999 Threads

Homework Statement Prove that snell's law ## {n_1}*{sin(\theta_1)} ={n_2}*{sin(\theta_2)} ## is derived from using euler-lagrange equations for the time functionals that describe the light's propagation, As described in the picture below. Given data: the light travels in two mediums , one is...

This is probably my misunderstanding, so please clarify. In a region of empty space, there are two point charges with the charges+Q and -Q. Exactly in the middle of the two charges (distance r from both charges) is point P, colinear with the centers of both charges. A Gaussian surface that...

Homework Statement Consider air to be made up of only N2 (78 mole %), O2 (21%) and Ar (1%) Estimate the mole fractions of each in both the liquid and gas phases if 1 mole of air at 300 K and 4 atm. total pressure were cooled to 65 K in the same volume Homework Equations Raoult's law Pi = Pi*...

Wiki states: Photon upconversion (UC) is a process in which the sequential absorption of two or more photons leads to the emission of light at shorter wavelength than the excitation wavelength. https://en.wikipedia.org/wiki/Photon_upconversion Is it possible to have the emitted light with the...

Gauss’s law is stated as follows What exactly does E describe. If you use a Gaussian cylinder for example, where does the value of E describe the electric field?

Homework Statement I am supposed to make a project based on this simulation, I am trying to see what is happening: https://phet.colorado.edu/en/simulation/faraday If I go to the "Transformer" tab, I have an electromagnet and a circuit consisting of a loop of wire and a light bulb. I can...

We took today in a lecture gauss' law for magnetism which states that the net magnetic flux though a closed shape is always zero (Monopoles don't exist). The professor explained/proved it as following (Since it needs math theorems): Draw any shape. From the fact that any magnetic field line that...

Homework Statement I am having a issue with the question, when I check the solution to the problem, I can't seem to make sense of how they have derived there equation. Q: By analyzing the superposition of frequencies and amplitudes in the radial velocity data for a star 55 Cancri A, the first...

To find the electric field from an infinitely long charged rod you can use gauss’s law with a cylinder as your Gaussian surface. I don’t quite understand by this works. Wouldn’t the electric field given by the equation only be the electric field cause by the charge within the cylinder? And if...

Homework Statement A helium nucleus ( 2 protons and 1 neutron stripped of its electrons is 0.03 mass from a single proton. What is the direction and amount of the acceleration of the proton?Homework Equations acceleration= force net/ mass force= Kq1 xKq2 / r^2 K is constant q1 is the charge of...

How can I derive mathematically law of composition of velocities from time dilation and length contraction But please use only algebra .Don't use four vectors and space time diagrams.

Homework Statement A point charge q=−5.0×10−12 C is placed at the center of a spherical conducting shell of inner radius 3.5cm and outer radius 4.0 cm. The electric field just above the surface of the conductor is directed radially outward and has magnitude 8.0 N/C. (a) What is the charge...

Good day All! I have an issue solving this question According to my basic understanding, the displacement current goes from the positive plate to the negative plate, so whether the capacitor is charging or discharging the magnetic field direction should remain the same, but here is the the...

So it is stated that exothermic reactions are the ones where the heat of reaction is positive and endothermic reactions are the ones where the heat of reaction is negative. My question is: why is this so, when in the 1st law of thermodynamics, where ΔU=Q+W it is stated that Q is positive if...

Hi. Usually the law of the lever or similar force laws for simple machines are derived using $$W_1=F_1\cdot s_1=F_2\cdot s_2=W_2\enspace,$$ sometimes called "Golden Rule of Mechanics". However, these force laws also hold in the static case where no work is done. Is it possible to derive the law...

Homework Statement Question ==== An infinitely long insulating cylindrical rod with a positive charge ##\lambda## per unit length and of radius ##R_1## is surrounded by a thin conducting cylindrical shell (which is also infinitely long) with a charge per unit length of ##-2\lambda## and radius...

See the screenshot for the full problem. 1. Homework Statement We're given a pulley with one side hanging (A) and the other on an inclined plane (B). We are also given that the mass of A is 15 kg and the mass of B is 17 kg. The angle of elevation of the inclined plane is 32 degrees. The...

Hi all! Wanted to know if this is along the right lines, or if I'm missing anything... Any help is greatly appreciated :) 1. Homework Statement Explain the connection between a graph of potential difference versus current, and Ohm’s law. Homework Equations slope = rise/run V=IR R=V/I The...

Hi, I'm new here. Could someone provide some guidance on how to start this problem?

Hi there, Just to map out my question, I am thinking about cart 1 which is a motorized cart and cart 2 -- a cart with a heavy object on it. There is an acceleration rightward. I understand that Fc1onc2 = -Fc2onc1 which means that the forces do not cancel out as they are applied on different...

Homework Statement Find an equation for the net electric field at a point, above and between, two infinite line charges, one with line charge density λ and the second with line charge density -λ. The point is a distance R from both line charges, a distance y above the midpoint between charges...

Homework Statement A capacitor has two square plates that are d apart. Each plate is L×L. The capacitor is initially uncharged. (a)Calculate the work required to move q of charge from one plate to the other. (b)Calculate the work required to move an additional q of charge from one plate to the...

Homework Statement I need to calculate a spring constant using measurements from a Hooke's Law Apparatus, a spring, and some weights. The weights are hung vertically from the spring and the distance is measured from the equilibrium point of the spring. If I'm solving for k, then k=F/x. I do...

the problem: Say we have the entire space uniformly charged. Then, the E field experienced by any point is zero, from symmetry.* But, it means that for any Gaussian surface, the flux though it is zero even though the charge enclosed is clearly not. Gauss' law seems to disagree with symmetry, but...

Homework Statement A 3-ft^3 container is filled with 2-lbm of oxygen at a pressure of 80 psia. What is the temperature of the oxygen?Homework Equations pV= nRT T= PV/nR R= 10.7316 psia x ft^3/ lbmol x R The Attempt at a Solution Hi everyone! So I understand how to use the Ideal Gas Law but my...

Hi, I'm trying to find temperature of stars using the stars' B-V magnitude by using the Planck law. However i do not know how to solve for T (assume other quantities are all given and determined first). Any idea how to do so? I already tried to do it but reach a dead end. Here I attached the...

This is not a homework question, but I read elsewhere that questions for self-study were required to be placed in this section. I had a question that pertains to the non-instantaneous transfer of information (limited at the speed of light, c) and how it would work in a thought-experiment...

I currently styding applications of Lie groups and algebras in quantum mechanics. U^{\dagger}(R)V_{\alpha}U(R)=\sum_{\beta}R_{\alpha \beta}V_{\beta} Where ##U(R)## represents rotation. Letter ##U## is used because it is unitary transformation and ##R_{\alpha \beta}## matrix elements of matrix...

Recently read this article on Physorg: https://phys.org/news/2018-01-efficiency.html My questions are: 1. If "converting" information into energy requires a system (the demon I suppose) having a photodiode, processor, laser (light trap) all expending energy in order to cause the conversion...

Homework Statement Homework Equations No current enters of leaves Opamp Terminals The Attempt at a Solution Red line is current path. Inverting terminal of Opamp -1 is at ground due to virtual ground concept, so Current = 2/1 = 2mA. This current goes through feedback path and then right...

initially my attachment/picture has been cut off that link http://sun.stanford.edu/~sasha/PHYS780/PLASMA_PHYSICS/phys780_2014_l13.pdf page 6 Also I would like to put into words that divergence of current density is accepted as 0 in continuous loop( no capacitors exist...). But if you look at...

When we use Ampere's law, the most basic case that of an infinite current carrying wire is taken whose magnetic field is evaluated at a distance r from the wire. However there's nothing wrong in using the law for non symmetric scenarios. If this is the case how do you explain the B field at a...

After a few recent discussions I have realized that I don’t know anything about a relativistic theory of materials. Does anyone have a good link for a reference about Hooke’s law in relativity, or something similar. Homogeneous isotropic linear media is fine.

Homework Statement "A particle with charge -3.03 nC is at the origin, and a particle with negative charge of magnitude Q is at x = 49.0 cm. A third particle with a positive charge is in equilibrium at x = 20.8 cm. What is Q?" Homework Equations I'm fairly certain that Coulomb's Law is the...

When we try to find magnetic field due to a set of current carrying wires in a region we draw an imaginary amperian loop and using ampere's law find the magnitude of the magnetic field. ##\oint \vec B \cdot d\vec l = \mu_{0}i_{enclosed}## The RHS involves only the enclosed current inside the...

Equation: ΣF=Σk(qi)(qj)/(r^2) Question: Considering more than a couple of particles. How can a net force on a charged particle be calculated if Coulomb's law is under the restriction of static forces? Thanks!

Homework Statement If equal masses of Xenon, Argon and Neon are placed in separate flasks of equal volume and same temperature, which one of the following statements is correct: a) The pressure of Neon flask is greatest. b) The pressure of Argon flask is greatest. c) The pressure of Xenon flask...

I've got this, calculate the mass of a non volatile solute (molar mass 40) that should be dissolved in 114 g of octane to reduce its vapour pressure to 80 percent I do this, v.p = v.p_pure * mole fraction of solvent in solution we have 1 mole of solvent and let's take n moles of substance so...

If the coulomb's law instead of following an inverse square relationship, follows an inverse cube relationship, How would it affect an isolated charged conducting sphere? How would it's field vary within the volume and how would the volumetric charge density be affected? Please give in some...

Hi everyone. I found this image online that made me question a couple of things that might be a bit humiliating to ask: I always thought that tension is simply a pulling force, meaning that the mass is suspended because the tension force pulling the mass is equal to the weight force of the...

Hey guys, is anyone here familiar with birefringence in uniaxial optical media? In such a medium, there are only two types of polarizations allowed for a wave to propagate. A wave with any other polarization will split into two waves with the allowed polarizations (ordinary + extraordinary wave...

Hi, From the movement of air molecules electricity is generated. The kinetic energy of the air molecules is converted into usefull energy and the air is cooled down. Why do windmills not violate the second law of thermodynamics?

At high school, we saw without demonstration the fundamental principle of dynamics (2th Newton's law), i.e : $$\sum \vec{F}=m \vec{a}\,\,\,\,\,\,\,\,\,eq(1)$$ after, at university, we saw another expression of this 2th Newton's law : $$\sum \vec{F}= \dfrac{d\vec{p}}{dt}\,\,\,\,\...

Suppose the hydrogen atom consists of a positive point charge (+e), located in the center of the atom, which is surrounded by a negative charge (-e), distributed in the space around it. The space distribution of the negative charge changes according to the law p=Ce^(−2r/R), where C is a...

Homework Statement Homework Equations Fs= μs*N ΣF=ma The Attempt at a Solution [/B]

Homework Statement Homework EquationsThe Attempt at a Solution I believe none of the options are correct . Option c) would have been correct if E represented peak voltage , I represented peak current and Z is used instead of R . But I suppose the question is considering E to be E(t) and I...

Homework Statement Homework Equations F = ma Fr = uK * N The Attempt at a Solution My answer is 7 but it is not one of the choices Thanks in advance[/B]

Homework Statement A charged, straight line/rod of infinite length has a Discrete uniform distribution of charge, has a linear density of λ and is at a distance d from a sphere with a radius of R. Find the entirety of the Electrical Flux that is caused by this charged rod, which passes...

Homework Statement An uncharged, unconductive, hollow sphere with a radius R of 10.0 cm, surrounds an electric charge of 10.0 μC, which is found at the beginning of the axises, in a standard cartesian system. Parallel to the z axis, a small drill with a radius r = 1.00 mm opens a hole in the...

I shall try to expose my question as briefly and clearly as possible. Within a very old and classical approach (Newton), discussions take place in a three-dimensional Euclidean space and the concept of force is represented by a vector which is proportional to the mass of the object at hand (m...