Difference Definition and 1000 Threads

I have seen and gone through this thread over and over again but still it is not clear. https://www.physicsforums.com/threads/vectors-one-forms-and-gradients.82943/The gradient in different coordinate systems is dependent on a metric But the 1-form is not dependent on a metric. It is a metric...

Homework Statement In a circuit, a capacitor (Xc=30Ω, R=44Ω) and an inductor (Xl=90Ω, R=36Ω) are connected in series with an AC source (ƒ=60Hz, V=200V). Determine: 1-current intensity 2-the voltage across every component in the circuit. Homework Equations Z=√R²+(Xl-Xc) Where: Z is the...

Homework Statement If a positron (or electron antiparticle) beam is accelerated across a potential of 20 kV, find the final velocity v of the particles. Do this problem TWICE, once using MKS units (J for energy) and a second time using "modern" units (eV for energy). Use the following values...

When it comes to analytic geometry, I am little confused about the use of vectors. For example, throughout high school, one works in ##\mathbb{R}^2##, and geometric objects such as lines are described using equations relating two variables, the x and y coordinate, such as y = 2x + 1. However...

Homework Statement Two parallel-plate capacitors have the same plate area. Capacitor 1 has a plate separation twice that of capacitor 2, and the quantity of charge you place on capacitor 1 is six times the quantity you place on capacitor 2. How do the potential differences across each of the...

Hello everyone I want to know what is the difference between Absorption and Extinction spectra. and in term of experiment how can get extinction spectrum. Thank you

Homework Statement ** sorry, answer in the book doesn't make sense ** A british concord and a French concord flew in opposite directions around the world, a distance of 40K km. The BC covered half its distance at 2500 km/h, and the other half at 1000km/h. The FC spent half its flight time at...

Online it says that the integral is the opposite of the derivative. So x^2 is the integral of 2x. So if f(x) = x^2 , does that mean that the integral is just the function itself? Basically whatever f(x) equals? Thanks in advance

I have a problem understanding the concept of potential difference. I get the picture of seeing it as a height difference for example (rock or water that would fall down) but what confuses me is that many times the order of elements in a circuit does not matter. To explain myself better: if I...

Homework Statement Can someone explain why for the first derivative 3 point forward difference formula is 4f(x-h) - f(x-2h) ?? Homework EquationsThe Attempt at a Solution Why it's not f(x-h) - f(x-2h) ? Is there anything wrong with the notes ?

Trying to calculate the power of a pump, it's pumping water. It has a flowrate in and out in kg/s. Surely I should look up the enthalpy values and just mutiply with the flow rate to get power in kW. However I know that if I convert flowrate to m3/s by dividing 1000 and multiplying by the...

Hello, sorry, I do realize that this question has been asked before but there are just a few things I would like to figure out. So, in my mind the differences lie in knowing the states that the system could end up in, and also the difference in the probabilities. Is this thinking correct...

why don't we feel the difference in Earth's angular velocity between standing on north or south pole versus standing on the equator? Thank you

I don't know much about biology but the origin of life has always been very interesting to me so I sometimes check to see whether there was any progress or not. Now this recent development seems so important but I don't quite understand it because I don't know the difference between the Bacteria...

Homework Statement a.) Find the resultant of the two waves: Phasor method E1 = 4cos(ωt) & E2 = 3cos(ωt+\frac{\pi}{2}) b.) By algebraically writing E1 = 4cos(ωt+α-α) & E2 = 3cos(ωt+α+\frac{\pi}{2}-α) Choose α to make the wave have only a cosine termHomework EquationsThe Attempt at a...

Hello, Ok, so I’ve been searching about this for a while and there seems to be a difference in explanations that confuses me. What concerns me is the exact detailed physical mechanism that makes particles cause a scatter of a photon and an emission of a photon. The Wiki page about scattering...

Hi. I'm trying to model the attenuation (extinction) of a weak laser through a gas sample using the Beer-Lambert law. I've found that the attenuation cross section can be written as the sum of both a scattering and absorption cross section, however I'm having difficulty finding a source that...

Paratenic host 'In parasitology, the term paratenic describes a host that is not necessary for the development of a particular species of parasite, but nonetheless may happen to serve to maintain the life cycle of that parasite' until they are transferred to an obligatory host. (from Wikipedia...

Homework Statement For this question , i am not sure how to get the Q , Can i use the middle part instead of the right part ? Homework EquationsThe Attempt at a Solution if i use middle part , my ans would be (0.35)(0.025)(0.18676-0.175) = 1.03x10^-4 , which is different from the ans . Is it...

Hi, I read a chapter about the Heisenberg-model, and then something about the Hubbard-Model. The Heisenberg-model just shows, that neighbouring spins allign antiparallel if J<0. The Hubbard-Model says, that there is a hopping probability t and an Coulomb replsion, so that a material becomes...

Homework Statement Homework Equations p=ρgh Q=A1U1=A2U2 Bernoulli: p1+½ρU12+ρgz1=p2+½ρU22+ρgz2 The Attempt at a Solution [/B] So I got that the pressure difference is gh(ρm-ρ). So I rearranged Bernoulli for p1-p2 to get (assuming the potential is the same I eliminated it)...

When solving for the hydrostatic force on a surface we use the height to the centroid(hc), then when using the point of application we use the y coordinate of the centroid(yc), however shouldn't they be the same since they both start from the top surface and reach down to the object surface on...

When considering the magnitude of the magnetic field at a certain point (##P##) away from an infinite/finite wire, I can't understand how an infinite wire would generate a stronger magnetic field (##B##) in contrast to a finite wire that has the same dimensions and current applied, at the same...

Can somebody pls explain this to me?

I know that HCl is a compound whose 1 molecule is composed of 1 hydrogen and 1 chlorine atom bonded co-valently to each other, the bond being polar co-valent. It exists in gaseous state at room temperature. When HCl gas is dissolved in water, it dissociates to furnish H+ ions and thus HCl...

Hi, In a current generated by an alternator, can we really say that there is a potential difference like in a battery? The magnetic field exerts a force on the electrons which makes them move. We can calculate the work done to the electrons in joules, and we can divide this energy by the...

According to Ohm's law, "Physical conditions remaining the same, the electric current flowing through a conductor is directly proportional to the potential difference across the two ends of the conductor" I have two conceptual queries: FIRST When the ends of the conductor are not connected to...

Homework Statement Which algebraic expressions must be solved when you use finite difference approximation to solve the following Possion equation inside of the square : $$U_{xx} + U_{yy}=F(x,y)$$[/B] $$0<x<1$$ $$0<y<1$$ Boundary condition $$U(x,y)=G(x,y)$$ Homework Equations Central...

Okay, so I've reached the Work Chapters in my textbook, and I've noticed some contradictions, especially in what consists (and what doesn't) an Isolated System, plus the external and/or applied forces. For example, in one of the "Speed Questions" it categorizes a single cube as a non-isolated...

Please take a look at this picture and tell me why using each of these approaches will give me different angles. When measuring the length (this is the outline of a razor) and using the equation to find the angle from the dot product, I get 53.6 degrees or so. When I just simply take the arc...

Homework Statement I have been working through “Basic Concepts in Relativity and Early Quantum Theory” by Resnick and Halliday. I've read about and done most of the problems about time-dilation, length-contraction, and Doppler effect. But then I got to problem 2-76, and I’ve been swirling in...

Hello all, this is related to a project that I am working on. It is not directly related to the project but as part of it, I thought it would be a good idea to check the temperature difference that I need to maintain in order to effectively transfer a certain amount of heat between the TH in a...

While studying the difference between sound and light, I am puzzled by the following statement in this blog: Is this just another way of saying it doesn't need any medium? The Transmission medium Wikipedia page makes me think the vacuum of space is its "medium".

Good evening everyone! Given that I have no experience in antenna physics or related areas, I'm studying a paper for a project I will be involved. It is an image sensor for THz e.m. waves and exploits micro-bowtie antennas to "capture" the signal and convert it through a standard CMOS imager...

Let A,B,C be three sets . Prove Ax(BΔC)= (AxB) Δ (AxC) I tried to start with this : Let p be an arbitrary element of Ax(BΔC) then p=(x,y) such that x ∈ A and y ∈ (BΔC) x ∈ A and (y∈ B\C or y∈ C\B) (x ∈ A and y ∈ B\C) or (x ∈ A and y ∈ C\B) But I don't know how to continue or if I should even...

What is the difference between an effective G-action on a manifold and a free G-action on a manifold? Including a screenshot of the page from Isham where they are defined. Seem to be the same thing to me. Maybe I'm just not seeing the difference?

Hi everyone! What is the difference between coherent and elastic scattering. Maybe the elastic scattering implies that there is not loss of energy, whereas the coherent scattering implies that the wavelength of a ray (or rays) is the same before and after the scattering? Thank you in advance.

I am confused about determining when two or more functions are linearly independent. My textbook notes that the Wronskian can do this, but then it also mentions the definition of linear Independence, that the linear combination ##c_1 f_1 + c_2 f_2 + ... + c_n f_n = 0## only has the trivial...

Homework Statement In the figure below, what is the potential difference Vd - Vc between points d and c if E1(of 1st battery) = 4.7 V, E2((of 2nd battery) = 1.4 V, R1 = R2 = 11 Ω, and R3 = 6.7 Ω, and the batteries are ideal? http://farm6.static.flickr.com/5053/5469093809_53c7fe57f4.jpg...

My question is as follows, given a hermitian operator, what's the physical difference between performing a measurement on a particle to get an eigenvalue of said operator and acting on the state of the particle with said operator? What prompted my question is the swap gate used in quantum...

What is the key difference between Otto engine and Carnot engine? Other than it is reversible or not, it seems to me they are so similar. Thanks.

Hello everyone, I know this will sound slightly silly, but I'm feeling a little inadequate about my physics GRE score. I recently took it and scored an 860 (80th percentile), but I'm wondering if not getting in the 900s will hurt my chances for a top grad school. Do most schools recognize that...

Recently a friend wanted me to help him tune a stainless steel volume used in the production of kitchen utensils, and finally I chose the ss201 and ss304, but I do not know which of the two which is better?

Hi, I have a question about something that I was recently told. They said that if you have a positive charge on one end of a wire and the other end is connected to ground, which they said was negatively charged, a current will be produced due to potential difference. Is this true, and does...

I am a high school student, so I know only the basics of X-Rays.I simply know about continuous X-rays, cutoff wavelength and threshold wavelength. Now if I increase the potential applied to the X-ray tube, I am certain that the minimum wavelength of emitted radiation decreases. (I say this using...

Is there any inherent difference between amplified spontaneous emission and stimulated emission? Is not stimulated emission simply the mechanism by which ASE occurs? Is stimulated emission just a broader term? I've read the two terms in literature and just wanted to ensure I understood the...

if you look up the cross section in Janis books, usually for same reaction, different cross sections are quoted by different laboratories. For example, the values of thermal neutron capture reaction 9Be(n, r)10Be: EAF-2010, 0.0075b ENDF/B-VII.1, 0.01b JEFF-3.1.2, 0.0088b JENDL-4.0, 0.0085b...

What is the difference between apparent power and complex power? How to differentiate them?

Homework Statement Ions having equal charges but masses of M and 2M experience a constant electric field while they travel a fixed distance d and then enter a uniform magnetic field perpendicular to their path. If the heavier ions follow a circular arc of radius R, what is the radius of the arc...

Hi All, I was wondering if someone could answer these questions for me please? Q1. If I stuck an antenna out, will it receive all the different signals e.g. Music Radio, TETRA, WiFi? Q2. What is the difference between these? I thought it was the frequency e.g. TETRA uses 300-400 MHz, WiFi uses...