Dissipation Definition and 175 Threads

I am confused about the concept of a power dissipation limit for a resistor. Basically for a resistor the product of the current through it and the potential across it should not exceed 0.25 watt otherwise it starts to heat up and act in a non-linear fashion. Is this value just a constant or is...

Homework Statement A magnet of mass 0.10 kg is dropped from rest and falls vertically through a 35.0 cm copper tube. Eddy currents are induced, causing the copper to warm up. The speed of the magnet as it emerges from the tube is 1.50 m/s. How much heat energy is dissipated to the environment...

Homework Statement The system can pivot at point O and I am taking small angle approximations. I am trying to determine the Lagrangian, ##\mathcal{L} = T - U## for the following system: Homework Equations E-L equation with dissipation: ##\frac{\partial\mathcal{L}}{\partial q_i} -...

Okay, I created this topic because the other one seem to get no responses?! I found this paper that was useful to me : http://people.bath.ac.uk/enscjb/airtex.pdf It mentions the figure 2.0 - 2.6 L/min/kW. Is this kW, the bhp? Question 1:For a Nissan Maxima (3.5 L engine), could I take this...

Homework Statement Basically, I need to know the power dissipation (W) for three resistors using aw 12V battery: 120, 80, and 50 ohms. https://webwork2.uncc.edu/webwork2_files/tmp/Fall2014-Engr1201-Common/img/2ff2f0ce-cb10-3786-8109-c42346130316___1a2e5eeb-8657-3983-941f-b7d8a9123afa.gif...

Hey Guys, Can you see what is wrong with this circuit? It looks fine to me but I am being told that it is incorrect and will not work. I am pretty sure I am wrong and am willing to ask for help in understanding why this wouldn't work. Please see attached picture for further info and any...

I want to know the meaning of energy dissipation...is eergy dissipation and energy consumption are same things?? inductor and capacitor store energy which can be used later... what is then energy dissipated?? is it the heat loss in these elements?? I mean..heat loss is what we say energy...

Hi I'm trying to model the drag effects in using Lagrange Mechanics and trying to include the effects of aerodynamic drag. I've read up on the Rayleigh Dissipation functions in Greenwood's "Advanced Dynamics" and a few other books but they always provide the Rayleigh function for drag forces...

Hello everyone, I'm studying the finite strain theory and have come across the maximum dissipation principle. It implies a dissipation function defined as D=\tau:d-\dfrac{d\Psi}{dt} \tau denotes the Kirchhoff stress tensor, d the eulerian deformation rate and \Psi=\Psi(b_e,\xi) the free...

Hello, This is my first post on this forum and I better warn you that there maybe some poor grammer and spelling mistakes. Given what I had to aggree to in order to register I'd like appologies in advance to all those people who are offended by such things. I'm looking at a problem with...

I am looking around for some sort of equation regarding optical power dissipation of light (ultraviolet light in particular) in the atmosphere but i cannot find anything. I know that UV light obeys Rayleigh scattering but I don't know much else. I'm trying to figure out for example, if I shined...

Homework Statement i let r = 1 ohm, so i get effective r = 1.5 ohm, , since P=VI, i get my I = 8A, so i get the power dissipation of RESISTOR P = 8W , so the 4W remaining for both Q AND R , why power of R is 2W? i hope someone can explain this. Homework Equations The Attempt at a...

I have two questions, one is how to calculate the heat dissipation from M1 and M2, and the second is how to calculate the maximum frequency M2 can handle. The LED is a Cree XLamp XQ-D running at 3.1V and 350mA. There is a 3.1 volt drop across the LED leaving 1.9V across M1, M2, and R2. I did...

Hi Guys--and Gals? Here's a wierdie; One is always collecting potential on our bodies, frequently called electrostatic voltage. I've found sound research that it is beneficial to "earth" or ground ourselves as often as possible to drain this off. Those last words are the question: does this...

Homework Statement A z-polarized incident EM waves hits a small charge (-q) bounded to a massive charge (+q) with spring constant k0 and frequency ω. (a) Write down the equation of motion (b)Find time averaged total power dissipated. (c) Find classical scattering cross section σ...

I got this question ( i won't include a lot of details because this is not the homework forum) where i need to calculate the power dissipation due to internal resistance. What i did is , i calculated total V and total R and I , then i treated the battery as a normal resistance ( eg. a 1kohm...

I need some information on power dissipation of metal chassis resistors. I have 47 ohm, 50W resistors. (digikey part #A102169-ND) I hooked them up to 24V. So current flowing is about 0.51A But the resistors get too damn hot to touch(48-55 deg C, just after a few mins(~5mins). The power...

Homework Statement So today in lecture, my professor talked about VRMS. I understand VRMS and its relationship to DC power dissipation, however, in lab today I became very confused. In lecture, we were told to use the VRMS value when applying Ohms laws/power equations (P=VI). Then, later, in...

Homework Statement (image attached) A). What is the total rate at which electrical energy is dissipated in the 5.0−Ω resistor? B). What is the total rate at which electrical energy is dissipated in the 9.0−Ω resistor? C). What is the power output of the 16.0-V battery? D). At what rate...

Homework Statement A capacitor C=8.00*10^-8F which has an initial charge q=1.4*10^-6C starts to discharge through a resistor R=3.00*10^6Ω at time t=0. Determine the total energy W dissipated as thermal energy in the resistor. Hint: use energy conservation. The Attempt at a Solution I...

difference "power dissipation" and "actual power dissipation" Hi, Is it possible to explain me the difference between "power dissipation" and "actual power dissipation" for a resistor ? I really can't understand the difference...

I know how to select a heat sink based on Power dissipation and max junction temp. But how do I relate this to CFM of a fan. How I calculate CFM based on pd and max junction temp?

Homework Statement Three resistors, R1 = 27 Ω, R2 = 42 Ω, and R3 = 53 Ω, are connected in a multiloop circuit, as shown in the figure. Determine the amount of power dissipated in the three resistors. Homework Equations Junction Rule Loop Rule The Attempt at a Solution I...

I am curious if someone can help be estimate heat sinking and dissipation in an Aluminum structure? What I am trying to do is is cool a hot liquid by just allowing it to heat the structure it is in since there is a reasonable amount of mass. Though the Aluminum structure is not designed...

Homework Statement I want to ask about a question which is related to dissipation of electric power. Here's a quick picture of my problem: R1=R2=R3=R4 R1 dissipates an electrical energy of 36 W Question: What is the electrical energy dissipated by R4? Please look at the circuit I've...

Hello there, I have a question on the dissipation and entropy. Let us consider a Newtonian dampener with viscosity coefficient η, pulled at a fixed rate e', immersed in an infinite bath at temperature T. The mechanical work input in time dt is then dW = ηe'*e'dt, and is all dissipated...

Homework Statement attached Homework Equations The Attempt at a Solution First I decided to find the equivalent resistance. Since r2 and r3 are parallel, this can be combined into a resistor of resistance r2r3/(r2 + r3). Since r2 is known, I went ahead and wrote that as...

Hello, I am wondering if anyone knows any correlations or equations that can give me the temperature of a wire due to power losses. I understand how to calculate the power loss in the wire, based on wire resistance and current (P=I^2*R) but how do I turn this into a heat transfer problem and...

Homework Statement An extension cord made of two wires of diameter 0.129 cm (no. 16 copper wire) and of length 1.2m (4ft ) is connected to an electric heater which draws 15.0A on a 120 V line. How much power is dissipated in the cord? Homework Equations P = IV R = ρL / A P = V^2/R...

Homework Statement A 3 m long copper wire that has a diameter of 6 mm is connected to a 9 V battery. a) What is the current through the wire? b) If wire a was connected to a battery for 1 second, how much energy would the wire dissipate? Homework Equations A = \pir^{2} R = \rho\frac{L}{A} i =...

Homework Statement A battery is connected across a uniform resistor R0. A sliding contact can move across R0 from x=0 to x=10cm at the right. Moving the contact changes how much resistance R is to the left of the contact and how much is to the right. Find the rate at which energy is dissipated...

Trying to put aside, somehow, questions of body elasticity, How long does it take on average for a body, in outer space, to start moving at constant speed, from the moment that force has stopped acting on it? Or is this question, totally dependent on elasticity, and if you don't take...

Hello everyone, this is my first post, and I hope I have put this in the right area. I am looking to understand something about the behavior of a low pass filter. When an alternating current is passed through a low pass filter, the higher the frequency, the lower the voltage output of the...

Right, so I was going over some old (basic) electromagnetism principles (to make sure it doesn't all fall out of my head). And I was thinking about two resistors in parallel, assuming some constant dc voltage across them. And I was thinking about the power dissipated by this simple circuit. And...

So, power lines are designed to deliver power at extremely high voltage to minimize energy dissipation. This was presented in lecture by the fact that I=PV, so for a given power high V => low I, and since (I^2)R represents the energy dissipation, this term will be minimized. That makes sense...

Equation (p=i^2 * R) seems to suggest that the rate of increase of thermal energy in a resistor is reduced if the resistance is made less. "Eq" : p =v^2/R seems to suggest just the apposite . How do you reconcile this apparent paradox?

Hello, I have a loop antenna I have been messing around with for a few years and I understand most of the physics behind it, especially with regards to Faraday's Law of Induction; however, I'm trying to work backwards now to determine a source voltage at a distance. For example, if a...

Is there an equation that deals with the dissipation of sound waves in air? As in, how much they die out with distance, because we know they must, otherwise you could hear me talking now!

Is the equation right ? How do i solve it ? Thanks in advance and sorry about my poor english or something else

Hi all I need an some help on thermodynamics. I want to install a camera outside of my house, but the camera can only operate between 0 and +55 degrees celsius. Now I want to make an isolating box around it, and wanted to calculate how thick the material of the box should be to allow outside...

Homework Statement Problem: A 2.0 kg block oscillates up and down on a spring with spring constant 240 N/m. Its initial amplitude is 15 cm. If the time constant ("tau") for damping of the oscillation is 4.0 s, how much mechanical energy has been dissipated from the block-spring system after 12...

Calculate the power dissipated in R1, R2 and R [/b] Previously i worked out the Current I1, I2 and I3 so i planned to use this to calculate the power dissipated; For current i got; I1= 0.8409 A I2= -0.4545 A I3= 0.39 A I used I^2/R to get the following answers R1 =...

Friends: I am wondering about heat dissipation when you have imaginary numbers. Lets say a current I = (3 + 4j) Amps is going through an impedance Z = (2 + 3j) Ohms. What is the amount of heat dissipated by the impedance? I think that you take the magnitude of the current, |I| = 5 Amps, and...

This question is in reference to the diagram here: http://imageshack.us/f/17/ecediagram.jpg/ Find the average power dissipated on the resistor. Assume Vth for the diodes is 1V, N1 = 1000, N2 = 100, the transformer is ideal (non-lossy), and V(t) is a purely sinusoidal voltage with frequency...

the equation P = (E2R) / [(R-r)2 + 4Rr] We say that when R=r , P = E2/4R which is said to be maximum.. But if I say R→∞ , then r→0 and then P = E2/R which is greater.. So, shouldn't power be maximum for max R ?

During a Lab we had a simple purely resistive circuit hooked up to a 10 VDC power supply with an adjustable voltage output. In order to determine the power dissipated by the circuit we were asked to determine the source voltage while the circuit was DISCONNECTED... we were not told why... In the...

I've been looking over how to find power dissipation for voltage regulators, op-amps, comparators, logic gates, and amongst other things. Ive looked at some resources and I'm not getting what each variable means. From what I understood so far I've seen PDstatic = Vcc*Icc where Vcc and Icc...

i got part (a) by using the equation Vab + E - Ir Which gives 26.57V (also the current = 1.171A) Having trouble getting the power dissipated, any ideas?

Homework Statement Heater dissipates 500W when applied potential diference is 110V and wire is 800C. How much power would it dissipate if the wire temperature were held at 200C? Homework Equations a=4.0e-4 p=V^2/R Rf=R0(1+a(T-T0) where R is resistance after temp change...

I am currently working on a small personal project. It is a small under-water generator/ motor so the setup is as follows. The generator and gearbox are mounted on steel struts within an air-tight nacelle of sorts which is cylindrical and made of steel. The nacelle is submerged in cold water...