Source Definition and 1000 Threads

Mean Value property (harmonic functions) with a source?? Homework Statement I understand that the heat equation may yield ∂u/∂t=0 on the LHS and on the RHS we may still have Uxx+Q where Uxx is partial with respect to x twice and Q is a heat source. U in our case may be the temperature...

Homework Statement One microphone is located at the origin, and a second microphone is located on the +y-axis. The microphones are separated by a distance of D= 1.21m. A source of sound is located on the +x-axis, its distance from microphones 1 and 2 being L1 and L2, respectively. The speed of...

1. Homework Statement Find the total charge on a circular disc of radius ρ = a if the charge density is given by ρs = ρs0 (e^−ρ) sin2 φ C/m2 where ρs0 is a constant. Are the two limits of integration from 0 -> a for ρ and 0->2∏ for φ? In the example given in the notes, ρ varies, instead of...

Homework Statement i attached the problem. I am unsure how to solve this problem. I applied KVL and got 15-1I-2vx-vx-2I=0. Where I is the current in the circuit. From that equation I have 2 unknowns, so I obviously have to find I. To find I I'd have to find Req, but I don't know how the...

Homework Statement Determine the power generated by the dependent source in the circuit shown below: Homework Equations Ix=V/R Pgen=V*I The Attempt at a Solution I made an equivalent circuit, but it may not be correct (resistors in parallel?): Ix=-(12V/(12/7)Ω)=-7A 2Ix=2(-7a)=-14A...

I'm working on a project that has a 7.4v rechargeable battery pack and I am going to recharge the pack with a solar cell. If the solar cell is only capable of outputing no more than about 2v, is it at all possible to charge the battery pack? Thanks!

learning C++ by reading the code of open source projects? Is there any resource that teaches C++ by taking an open source project (at the level of quake 3 for example)and explains the code step by step for some one who only knows the very basics . In my opinion It will be very efficient . I can...

Hi, I am confused about my solutions to the following governing equation: u_{tt}-c^2u_{xx}=F_{xx} For F=A(x)sech^2\left(\frac{x-c_gt}{B}\right) Where c,c_g,B \in \mathbb{R} and A(x) is a linear function. Also, we have c_g<c. Substituting physical values for the parameters, I...

http://www.openvsp.org/

Hello, I am not an electrical engineer but I do have a slight background in some electrical engineering concepts. My question is a general one about relays (more specifically solid state relays but I don't think that really changes my question). I understand that a relay gets a small input...

Hello forum, a battery is a voltage source: it provides constant voltage, regardless of the load connected to it. there is also a current source: it provides constant current, regardless of the connected load. Is there something like a power source, something that outputs constant...

All stars and Galaxies appear to give off the whole spectrum of electromagnetic radiation. If one views images of the distribution of background radiation in detail it appears to be filimetary in nature. Also if one views the distribution of visible matter in the universe it also appears...

Homework Statement Upon using Thomas Young's double slit experiment to obtain measurements, the following data was obtained. Use this data to determine the wavelength of light being used to create the interference pattern. DO this in 3 different ways! The Angle to the Eighth maximum is 1.12...

I am looking for some intuition into a way of looking at the Gauss curvature on a surface that describes it as the divergence of a potential function - at least locally. I am not sure exactly what the intuition is - but this way of looking at things seems suggestive. Any insight is welcome. In...

hi, 1. could somebody explain me in very simple terms what are sourcing / sinking I/O. 2. In which cases i have to think about these things while interfacing. 3. i did lot of browsing and studied but every time i get confused, suggest me a simple lab experiment so that i can do each of...

I need a constant current source ckt which can source current in the range of 0.1 to 1mA, with +/-1% tolerance, with Vcc 3.3v Any ideas? I found this - http://www.ecircuitcenter.com/Circuits_Audio_Amp/BJT%20Current_Source/BJT_Current_Source.htm But no info on tolerance. What happens to Io...

Not sure which section to post this in, but here goes. It's entirely my own words - might look like homework but it's for electronics. Multiple microphones are connected to a computer. A sudden sound, like a gunshot, goes off in the distance. These microphones are separated from each other by a...

Methane from natural gas could be a great source of energy (eg. in thermoelectric plants), but the need to curb CO2 emissions stands in the way. I wonder whether one could get useful energy from some partial combustion reaction of CH4, that yields H2O plus some carbon-containing solid that...

When I first encountered the term genetic mutation, I envisioned a gene that had somehow spoiled – like an orange with mole on it. A little research indicated that a gene is a linear string of amino acids that codes for a protein. The term mutant gene was being used to indicate a gene in...

I am stuck with this problem,the dependent current source is creating a big problem for me, please help. I have attached the problem.

What is the root source of "Light"? I'm not talking about converted/transformed energy via external sources, i.e. Electricity or heat transformed to Light. Whats the root source? Energy itself?

Homework Statement P15. The police car with its 300 Hz siren is moving toward a warehouse at 30 m/s, intending to crash through the door. What frequency does the driver of the police car hear reflected from the warehouse? (5 marks) Homework Equations doppler shift for an approaching...

Hi, This is a question regarding my employment. A centrifugal pump at the source tank sends fluid 200m using 3" hoses to a recieval tank. When the automatic valve shuts on the recieval tank the pump stops due to it having a pressure sensor.When the pump stops there is 8 Bar pressure on...

What would be the best way to produce 2,000 volts at a low amperage using 12V as the power source? I guess I just want to produce 2000 volts at a low amperage in a mobile environment?

hi all, I'm looking for a cheap (and by extension simple) circuit. i have a special pot (Piher's 10mm hex PT-10) that can't be changed. the pots can be physically changed but i have to use this type. the series has a 150mw power rating, with resistances of ...

Homework Statement I wasn't sure what section to post this in, but for my honors lab, i need to cite sources on values or theories that i include in my lab report like normal. Yet I'm having trouble finding a decent source for the speed of light and the index of refraction of air. I...

How much experimental evidence is there that the speed of light stays c between a source and target moving wrt to each other?

in the picture you can see the electrical network. in blue is the Current of each side of the electrical network. (did it with loop equations) i asked to find the Electric power of E and the Electric power of the Current source. so for E i found it and i got pe=11.4w. i also know what...

Homework Statement Find Vx using source transformation Homework Equations V=IR KVL The Attempt at a Solution After doing source transformation on the three pairs of current sources and resistors... KVL: -6+2I-Vx+4I-3+3I+5I-2=0 14I-Vx-11=0 but Vx=5I (is it? I'm not so sure about this)...

Hi. I'm investigating the idea of using a laptop battery for energy storage in a portable solar setup. The idea is charging the battery from solar panels, then power/charge other devices from the battery in low light conditions. I would like to be able to power/charge laptops and...

So I am enrolled into this course. And we are learning probability and statistics and all that good stuff. But one thing bothers me VERY much. I lie, a lot of things bother me about this course but here is the first one: Transformation of random variables. So far we have been...

This news alarms me. They say its not from Fukushima, so I guess some other nuclear facility has had a problem? http://www.iaea.org/newscenter/pressreleases/2011/prn201124.html

Homework Statement A sound source A and reflecting surface B move directly towards each other. Relative to the air the speed of source A is 29.9 m/s, the speed of the surface B is 65.8 m/s and the speed of sound is 329m/s. The source emits waves at frequency 1200 Hz as measured in the source...

Referring to following video, does anyone have any suggestions on how dowsing works to locate water source? Thanks in advance for any suggestions

Problem description: The problem is Kotitehtävä 7 in the attachement. The idea is to calculate the output power (both P and Q) of the current source. Attempt: I know the current through the current source (obviously) and want to calculate the voltage over it to get the power. I have...

I'm looking at this question and I can't seem to come up with an answer, don't the VL (inductive voltage) and Vc (capacitor voltage) just cancel each other out leaving you with Vr (resistance voltage) as the source voltage, but I don't see why VL and Vc are much higher than the source voltage...

Homework Statement none Homework Equations none The Attempt at a Solution maybe they are broken down just like glucose in metabolism?

Hi, I'm trying to simulate the ship traveling in ice. Basically, I would like to assume that the rigid body dynamics is sufficient to do the job since the main point here is the interactions between rigid ice fragments and the rigid ship. The fluid interactions with ice fragments should be...

What method is usually used to locate exact place of radio signal source? Do exist some type of radio signals, exact place of origin which is completely impossible to locate?Well,at least up to few hundreds of feets?

Homework Statement Superman is carrying a red lantern with wavelength 650nm. He flies toward you at a speed of 2.7x108 m/s. What is the observed wavelength?Homework Equations f'=\frac{f}{\left(1-\frac{v_s}{v}\right)} and f=\frac{c}{\lambda}The Attempt at a Solution I used the equation...

Homework Statement Superman has a blue light of wavelength 480nm. How fast must he fly away from you so that his light appears orange, with a wavelength of 600nm?Homework Equations f'=\frac{f}{\left(1+\frac{v_s}{v}\right)} and f=\frac{c}{\lambda}The Attempt at a Solution I used the equation...

As far as I know all light speed measurements done using light sources that utilized electrons. The nominal light speed measurement used laser which is actually exited electrons. The speed of X-ray radiation from synchrotron used accelerated electrons. The speed of gamma radiation also involved...

I'm relatively knew to fluid dynamics. I'm self teaching myself. Could someone explain what it means to say a function or vector is a source term? Are there any significant mathematical properties/uniqueness's? I'm working with vector matrices, so if you could explain in this context that...

Hi all, I need to use some numerical simulation programs. The source code is provided in Fortran 90 but I'm not able to compile it. I'm using G95 complier on WinXP, and the code are avilable at the following address: http://www2.fz-juelich.de/jsc/splim/ Could you provide any step by...

I don't know if this is the right place to post this question, but here goes. Whilst solving a circuit in class from a homework assignment, we arrived at a situation where a capacitor was in parallel with just a single independent DC current source. The question is, would current flow...

Homework Statement I recently got a problem that confuses for days, the picture for this problem is in the attachment field, is there someone can tell me that, if an oscillator is topology is described using the negative impedance model in the picture, should I have R>r to ensure that the...

I'm looking for Physics 101, where they start from the very bottom of the floor in the world of Physics. I'm not taking Physics 1 until next semester, but I only know a little about what I've seen on the science channel. Does anyone know of a good website or book that can start me off on...

The intensity of the sound from a certain source is measured at two points along a line from the source. The points are separated by 11.8 m, the sound level is 68.10 dB at the first point and 60.31 dB at the second point. How far is the source from the first point? Know: I = P/A =...

Currently digging in FreeCAD and I like what I see. Still very much in the development phase with lots of functionality that needs to be implemented. I've heard of DraftSight, not sure how well that works. The reason for this is that commercial CAD software is *wicked* expensive. Hundreds...

Homework Statement http://img5.imageshack.us/img5/2959/question2e.jpg Homework Equations - A current source in parallel with a resistor can be transformed into a voltage source in series with a resistor. R stays the same and Vs = R*Is The Attempt at a Solution I have tried it in two ways. Both...