Internal Definition and 957 Threads

I was reading about a case of total internal reflection in mirrors and something got me curious... Is there anything such as 'weak refractions'?? In the diagram of the mirror I saw, as a ray of light from an object entered a mirror, it was reflected by the silver coating, and then by the...

Okay so I have conducted an experiment to find the internal resistance of a battery pack by gradient of a graph of voltage against current. All so far okay. I went on to find the EMF also, again all so far okay. Now I need the short circuit current, and I can't find any information anywhere...

can anyone explain for me :)? I have no idea:(

Homework Statement How to demonstrate that U is minimized at constant V and S, while H at constant P and S? Homework Equations ΔS universe = ΔS system + ΔS environment ≥ 0 ΔU system = δq reversible + δw reversible = δq irreversible + δw irreversible ΔS environment = −∫(δq reversible / T) dU...

Homework Statement Helping someone regarding this Qns: A Battery is formed by four 1.5 V identical cell in series. When a external resistor of 31 Ohm is connected across he battery, the current is 280 mA. Find the internal resistor of each cell. Can someone help to solve pls? Thank you...

Is this process known as "total internal reflection"? Or is it called something else? What is the name of this process that causes the entire material to light up even though the light is applied only to one side? Take a look at the photos so you can see what I am asking about. Notice how...

Homework Statement Argon is stored in a container of volume 2L and a pressure of 5 atmospheres. The amount of gas present is 0.2 moles. Find: (i) The absolute temperature of the gas (ii) The number of atoms of gas in the container (iii) The total mass of the gas (iv) The total internal...

Homework Statement A voltmeter is connected across a cell in a circuit containing a switch and a 2Ohm resistor. When the switch is open, the voltmeter reads 12V. When it is closed, the reading is 8V. Find the internal resistance of the cell. Homework Equations I tried to use V=IR - is I...

A stone is falling under gravity in a vacuum. Is its internal energy increasing? Well, since internal energy(Microscopic level) is defined as the energy associated with molecules(Sum of kinetic energy and potential energy of the molecules). The molecules inside the ball will not gain any K.E...

H = U+ pV pV = nRT H= U+ nRT H= H (T) I don't understand the transition from U+ nRT to H (T) Can someone explain this? I get that H = U + pV But how is H= U+ nR

Homework Statement The figure below shows a ray of light entering one end of an optical fiber at an angle of incidence i = 51.0°. The index of refraction of the fiber is 2.05. Diagram link: http://www.webassign.net/walker/26-55.gif (a) Find the angle the ray makes with the normal when...

Homework Statement Find the lowest angle of θ1 given the apex angle is 60°. Air (n=1) is on the outside and inside (n=1.5) ϕ is defined as 60 degrees. Homework Equations The Attempt at a Solution θc = sin-1(\frac{1.00}{1.50}) = 41.81° To my understanding, θ1 must...

Homework Statement Use the law of conservation of energy to calculate the temperature increase expected from energy transferred to internal heat of the water. There is more than one way to do this. Consider a mass, m, of water which falls over the cascade. If you wish, you may take the mass...

Hello I am a first year Mechatronics major (yes its a real major), and currently looking into the effects that magnetic and electric fields have on combustion. I have a few questions. 1) Concerning the electric field effects are the ions carried on the wall that carries the corresponding...

If I have 2 electricly charged bodies orbiting one another, the binding energy must contribute to the gravitation of the system. Their reletive KE must also. So the total gravitational mass of the system is greater then the sum of the indivual objects. If I used a laser and gravitational lensing...

Homework Statement A battery has an internal resistance of 0.50 ohm. A number of identical light bulbs, each with a resistance of 15 ohm, are connected in parallel across the battery terminals. The terminal voltage of the batter is observed to be one-half the EMF of the battery. How many bulbs...

. About a car internal combustion engine. Lets suppose the engine torque is maximum at 3500 RPMs when the engine gets also its maximum load, let's say, a 90%. This kind of data is usually shown at WOT. My question is: if the throttle is not wide open, but half open, allowing the cylinders...

Did any of you, read this new paper by Olaf Dreyer ?.. Can someone elaborate a little, what this paper is about. Looks interesting and new i can't get my head around yet !... http://arxiv.org/abs/1203.2641 Internal Relativity Olaf Dreyer (Submitted on 12 Mar 2012) General relativity...

Today, the Norwegian police published its report on what, in their estimation, worked, and did not work, in Norway in the emergency profession on that Black Friday. A summary has been made in English, https://www.politi.no/vedlegg/rapport/Vedlegg_1665.pdf I haven't yet gone through it...

A simple circuit with 2 batteries and a resistor connected in series. The positive terminals are connected to each other via a 4.5 resistor. Their emfs and internal resistances are below. What is the resultant emf? battery 1: ε=6V r=1Ω battery 2: ε=24V r=0.5Ω resistor connecting...

Hello, I'am new here and having some troubles with understanding the difference between 2 related subjects. I learned that internal energy contains 2 main components: kinetic energy and potential energy. U=E_{K}+E_{p} The related first law of thermodynamics (for closed systems)...

Homework Statement I'm trying to understand two things: 1. How internal energy is distinct from kinetic and potential energy 2. The difference between internal energy and enthalpy. Homework Equations enthalpy ΔH = ΔU + PΔV internal energy ΔU = Q + W = Q - PΔV The Attempt at a Solution I...

I'm aware of the equation ΔU = Q + W ΔU is the change in internal energy which equals 3/2 nRΔT Q is heat transfer W is workdone so PV = nRT would it be correct to say that ΔP V = nRΔT? For isovolumetric process (i.e. no volume change, no work done), can i say that change in internal energy =...

Hello everyone, I am trying to work on this topic as my research. i plan on using a potentiometer but i want to be able to use the resistor (across the test cell) as the load and still be able to obtain two balance points. one for emf, and another for calculating internal resistance as the cell...

change in internal energy is a function of temperature. So if there is no change in temperature then there should no change in internal energy. But consider this example. work done in process work done(W)= nRT*ln(P1/P2) (Δ)T=0; so it's isothermal) heat supplied(Q)=0 (No heat is supplied...

Homework Statement a) what is the density of dry air when the surface pressure is 1010hPa and the temperature is 27°C. b) what is the internal energy of 1kg of dry air under these conditions? Homework Equations P=p*R*T where P is pressure and p is density. The Attempt at a...

Hi, I have already been familiar with that exterior symmetry is the spacetime symmetry. Such kind of symmetry has been depicted by Poincare' group. Then I am still find the concept internal space/internal symmetry ambiguous. And I cannot understand why put Spin in exterior symmetry not...

Assuming that the gas in these processes is an ideal one, is the change in internal energy in an isochoric process (volume remaining constant) the same as the change in internal energy of isobaric process (pressure remaining constant)? Mathematically I can derive that they're equivalent, but...

A 76 W light bulb with a resistance of 179 Ω is connected to a power supply with a 117 V. What is the internal resistance of the power supply? Express the answer with one decimal place. So my attempt has been this but I'm not exactly sure whether or not so just making sure this would be...

Hi All, I am trying to work through a QFT problem for independent study and I can't quite get my head around it. It is 5.16 from Tom Bank's book (http://www.nucleares.unam.mx/~Alberto/apuntes/banks.pdf) which goes as follows: "Show that charge conjugation symmetry implies that the...

Hi. Can anybody help me out with som calculations of internal forces in an arm-system? There's a easy explanation with this message.

Homework Statement See attachment ecxample001. Homework Equations See attachment D11. The Attempt at a Solution In the first equation (Cp/R = a+bT+cT^2...etc.), Cp/R is the constant pressure specific heat. The general formula for enthalpy change is h2-h1 = integral[Cp]dT, so does...

how would you determine an error at the 100C mark in a given mercury thermometer?Your answer should consist of a labelled sketch of the apparatus you would use and brief notes on procedure. Why is it important, at the same time, to note the atmospheric pressure? If the thermometer registers 103...

Homework Statement A block slides to a stop along a table top. Which is true? A. The work done by friction is equal to the force of friction times the distance that the block slid. B. The work done on the block is equal to the force of friction times the distance that the block slid. C. The...

I am reading on wikipedia about internal energy and the describe it as the energy required to create a system. Ithought that this was the definiton for enthalpy of formation. Was it meant by the definition of internal energy?

Hello everyone, Recently I have been studying cavity resonators. I noticed that all cavity resonators have air in them, but I was wondering what the effects would be if something other than air was used? For the sake of simplicity let's say we put a dielectric material in it with a...

Hello all, I have following questions dangling in my mind, with a positive attitude of seeking help i want put them infront you geneus people, in my earlier post i get a good result and now i want to more insight of the very matter. kindly help me. Using the concept of state of system, i...

what is the differece between internal conversion electrons, electron capture and auger electons? i don't understand. The name suggests electron capture and internal conversion electrons are the same thing... but then when i look it up internal conversion electrons seem to be the same as auger...

Homework Statement To a source of current, one by one are added 2 resistances, first R1=1ohm, then R2=4ohm. In both cases, in the same period of time (t=t1=t2), the resistors give the same amount of heat (Q=Q1=Q2). Determine the internal resistance ("r" small r) of the electric source...

u denotes internal energy; v denotes specific volume; T denotes temperature.

Hi, I am a postgraduate environmental science student (NOT a mathematician!) struggling through some necessary maths. Any help with the following (which I suspect will be relatively straight foward) would be very much appreciated. Please ask questions if I have not made myself clear. Homework...

Hi, I was wondering if anone knew what an internal CD or DVD drive case is most commonly made of. I was hoping to use it to do some welding so am hoping it is steet but not sure. Cheers

Suppose you have the simplest type of black hole - time independent, no angular momentum or charge, Schwarzschild solution, then you modify the situation by adding a stationary mass outside the event horizon (I imagined lowering this slowly on an idealised string). The question is, does this...

Hi all! I have a quick question. In my Physical Chemistry textbook, the author states, "For a closed system in equilibrium, the internal energy (and any other state function) can be expressed as a function of temperature and volume." Can anyone explain just how that is true? I'm quite...

Homework Statement If only an external force can change the state of motion of a body, how can the internal force of the brakes bring a car to rest? The Attempt at a Solution I think that it may be because friction between brakes and wheels converts kinetic energy into heat. Or perhaps...

Hi, I'm taking a thermodynamics class and I'm stuck on how work relates to enthalpy and internal energy. Does work done by a system equal change in internal energy, change in enthalpy or does it depend on the situation? The question I'm stuck on asks for the work produced by a steam turbine...

Hello, first post here. I had a bit of an odd question that I can't get my head around, but I think is possible. Given the environment described in the picture, can you measure the amount of gas that is flowing from the hole in the box given that the pressure in the box has stabilized at a...

Hi I am a bit confused about the difference between Internal and External Descriptions of Systems. Didn't find any doc on web about this. A Little help needed :-). Thanks Salil

Homework Statement In a closed vessel there was some water vapor. After the water vapor dissociated, the temperature decreased by 10%, and the volume by 20%. Find the change in internal energy. (U{initial}-U{final})/U{initial} Homework Equations The Attempt at a Solution Let's...

Homework Statement "A car battery has an e.m.f. of 12V and an internal resistance of 0.04 Ω. The starter motor draws a current of 100A. a.) What is the terminal p.d. of the battery when the starter motor is in operation? b.) If the headlamps are rated at 12V, 36W, what is their resistance? c.)...