Sources Definition and 517 Threads

Physics help please -- Sources of error in lab experiments Ok so i need some help with a few labs.. some I've tried out and a few i just can't get.. what i want to know is whether the limitations and sources of errors that i wrote down for each of these labs are correct or not and what i could...

Hi everyone, In our undergraduate electrical course,we came across current sources as theoretical concepts. Are current sources used in real life(such as in electronics)?How important are they? Thanks in advance. Chander

I'm sorry that this is probably in the wrong place, but I couldn't find a place to post where I am allowed to start threads which was relevant. I'm hopefully starting a degree in particle physics next year, I'm currently in my last year of high school. Myself and one other student at my...

What is the voltage across R2? You should convert the 4 V source and resistor into a current source as your first step. The first thing I did is create a second current source out of the 4 V voltage source and the series resistor R2. I called it I_2. I_2 = E/R_2 = 4V/100Ω = 40 mA...

Not sure I am posting this in the right subforum, if this is not the case, please feel free to move it. Anyway, the title about sums it up - I need to find a good source which offers a thourough treatment of Hamiltonian formalism for the explicitly time-dependent case - could someone possibly...

I have been acquiring some nice molecular models of graphene, buckyballs, and things like the model below. http://www.indigo.com/images/product/172.jpg One thing I have not been able to find are crystal models with the different orientations like face-centered cubic, body-centered cubic...

Just looking for some good science/engineering related reading

Hello all, I already know that the radiant intensity of a point light source falls off with the inverse square of the distance to the source. This, however, only happens in a vacuum. My question is, what is the more general law for a point source inside an opaque medium with a known...

Hey. Iam trying to understand how specification of the equation can lead to hetroscedasticity. This is stright out of my notes. Yt=B1+B2x2t+B3x3t+...+BkXkt+\gamma\varpi+ε^{}_{t} Yt=B1+B2x2t+B3x3t+...+Bkxkt+ε^{*}_{t} where ε^{*}_{t} = εt + \gamma\varpit Since Var(εt) =...

Question Two monochromatic light sources approach each other head-on with equal speeds, v=\beta c relative to the laboratory. When they pass each other, the frequency of the light each receives from the other is halved. Show that \beta =3-\sqrt{8} Attempt at solution I have tried to...

Hello Everybody, My question is: Why when a resistor is in parallel with a "short circuit" the voltage across the resistor is zero, & so will the current passing through it? But when instead of a resistor we have a voltage source, this is not the case? "I was informed that the voltage source...

Not being an electrical engineer, I have always wondered how sources of AC power are matched when joining a common grid. I assume the power is generated at 60 hertz from each source but how is the match made so sources are in phase with one another? For instance, suppose an individual could...

Homework Statement See attached image Homework Equations Thevenin's theorem Node voltage method? The Attempt at a Solution So if I want the current Io, I believe I need to treat the 1K resistor as an open circuit in finding the Thevenin equivalent. I think setting ground to be the bottom...

Hi all, I am struggling to find any elementary material on the "gradient flow of a functional" concept. From introductions in advanced papers I seem to have understood that, assigned a functional F (u), the gradient flow is charactwerized by an equation of the type Du / Dt = P u , where P...

You are in a dark room with no other sources of light The walls are painted black, so no light is scattered from walls You have two point sources of light of equal power + same height about ground They are 10 feet apart You stand a thick rod vertically in middle of two, and 4 feet in...

Hi all, Apologies if this is the wrong place to post this but I can see lots of similar questions on this forum which aren't a 100% match for my question. I want to add a new interior light to my car. I want it to be on either when the headlights are on (power from the illumination circuit of...

Are there any peer reviewed sources of a theory which calls for a smaller... Are there any supported theories that call for a smaller, more accessible cosmos? Is anyone important suggesting that our fundamental understanding might be so wrong that we have an incorrect idea on the size and...

Hi all , is it possible to use the source transformation for dependent source ..? i guess yes because i came across a problem which asks to use source transformation to find Vx as shown : http://img571.imageshack.us/img571/2389/50111057.jpg and my solution was ...

Homework Statement Chain/product or quotient Homework Equations v=4sin^3 (4t) The Attempt at a Solution NB:@ Means teta(spelling might be wrong) 4sin^3 (4t) = 4sin (4t).sin (4t).sin (4t) using sin^2@=1-cos 2@ /2 v= 4sin (4t). (1-cos 2@ /2) = 4sin (4t)/2 . 4sin...

I am looking for somewhere to get a gear motor for a very low budget project, specs as follow: Voltage = prefer 110v, could be 12 if the price is right RPM = 15-20 Torque = 100 inlb Quiet as possible Reversible Something else that would be a bonus: Soft start and stop, gradual start...

Hi, I've just registered in the forum because I have a couple of Physics questions. I'm not a specialist, and furthermore English is not my mother tongue, so please be indulgent with me. As far as i know (please correct if not), only two sources of natural 'extraterrestrial' neutrinos have been...

Where to find sources on "Full Adders" Ok. So I have been reading and watching this stuff on 4 bit computers. I understand how to read binary code however I am having trouble with the concept of the "full adder" This is what I have been reading first off Does anyone know of a better...

Hello there, I am a Norwegian image maker. Unfortunately, I find discrepancies between photographs of the Earth from the Apollo missions (such as the blue marble) and images from the space shuttle and orbiters, which I cannot explain. They vary from the appearance of the atmospheric scattering...

Hi. I've been having problems finding some primary sources for my lab report for days. I've used my school's search engines, but I can't find anything appropriate to use. My report will sum up my experiment on how pH affects an enzyme's activity (catecholase catalyzing catechol and oxygen to...

I was playing around with some computer code to process some audio. As part of it, I needed to combine the audio from two different sources. Everything is in raw, uncompressed, 16-bit signed samples, at 48kHz sample rate. So now I'm thinking, do I add voltage, or add power? The sample values...

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...

Hello everyone I am trying to do an experiment involving a W bulb, in which I am completely dependent of knowing the temperature-resistivity relation of Tungsten in the temperature range 300 - 2500 K. The CRC handbook has some tables, but they have few data points and correlate poorly with...

When simplifying a circuit, can a parallel branch with a current source and a resistor in series be considered as just the current source? Also, if two parallel current sources 'point upwards' i.e. toward the positive rail, can I add them together as one source even if there are other...

Homework Statement Hi, i need to find the Admintace matrix and the current voltage vector. i know how to do it if i have only non dependent sources. but how should i work with the dependednt source? s should i take the dependent voltage source and turn it to current source with parallel...

This really isn't one specific problem per se as it is more of a conceptual issue, so I apologize for breaking away from the given format. I've worked through three problems involving a circuit where a thevenin equivalence circuit is required between two points, and all sources are dependent...

Homework Statement Hello, i was studying diodes for my exam on monday, but i had some struggle finding the Thevenin equivalent. Here is the circuit: http://img411.imageshack.us/img411/5336/schakeling.png Homework Equations I have no clue what to put here? The Attempt at a...

Does anyone know how to add more than two coherent sources that have different phases? An example might be a sound source and a receiver with sound reaching the receiver directly and by two reflections via different paths - maybe off a hard floor and hard ceiling. There's a good document...

Homework Statement I have this circuit: 0----------C----------0 U1___R C I1 I2 R C ___U2 0---------------------0 That's supposed to be two sets of Resistor, Capacitor, and dependent current sources all in parallel except with a capacitor separating the dependent current sources...

Homework Statement How far away can a human eye distinguish two car headlights 2.1 m apart? Consider only diffraction effects and assume an eye pupil diameter of 5.0 mm and a wavelength of 550 nm. What is the minimum angular separation an eye could resolve when viewing two stars, considering...

I'm curious to know what you all think of the future of energy. What type of energy do you think has the most promise for the future? What role do you think the various engineering disciplines will play? I'm really looking forward to the future of this whole antimatter factor haha.

WHY aren't voltage sources open circuited and current sources short circuited? Thevenin's theorem (and even Superposition Theorem) states that we need to 'suppress' or 'nullify' the effect of all sources. We do this by short circuiting voltage sources and open circuiting current sources. WHY...

Almost every EE I've talked to claims that you need to leave dependent sources in when using superposition to solve a circuit. I had a professor in undergrad who used to claim that statement is invalid. I've used his method since I learned it without any concern. I never saw any problem with...

We know that air molecules are subjected to random motion in different directions. A sound wave is a push toward these molecules to make a wave front to make them expand or contract in groups so that we can hear a voice message in our ears. The question is that what happens when different...

So I am doing research for the different energy sources that might be available for a space base in about fifty years from now. Some of these energy sources would likely be solar, fusion, fission, Nuclear, and I heard of radio - nuclide as well. What else could be used? In addition, does...

Homework Statement Wire #1 carries a current of 8.0A along the +x-axis. Wire #2 has a current of 6.1A along the +y-axis. What is the magnitude of the magnetic field at the point (1.4,1.3)m Homework Equations I'm not sure if Long straight conductor will be the right formula to solve for...

Homework Statement Solve power dissipated by RL Find a new values for RL that will receive maximum power solve for the maximum power that can be delivered Homework Equations Nodal analysis mesh analysis superpostion etc.. The Attempt at a Solution Hello guys, I've beein...

I'm doing some research on the 2007 Australian Federal Election. I seriously can't seem to find a lot of the things. I would appreciate it if anyone was to provide me any information and/or references. Or even anything else you have in mind.

I'm an experienced C++ programmer looking to learn Java SE 7. Because of the similarities of the language, you'd think there would be a tutorial out there suited for such people but I'm having trouble finding one. I've looked at a couple of Java tutorials that are tailored to C++ programmers...

hey everyone! i have flipped through quite a few textbooks on physics, chemistry and calculus, searching for one that presents motivates its derivations of equations and discussions of the concepts involved. primary sources (or those accounts of a theory written by its discoverer) which...

Quick question: how do you solve an ideal op amp circuit with the two terminals connected to independant power sources?

In the last few days I have read some horror stories of employees being abused by companies (extremely long hours and hire-and-fire etc). I do like to question of reliability of some of those stories but then instead of reading of random stuff off some random websites on the internet, i would...

Well folks, I will be sitting an exam tomorrow morning at 9am in which I have to travel 2 hours prior and maybe fit in an hour of revision. Anyone recommend good energy sources for the 3.5 hour exam? :-) I was thinking redbull drink...:devil:

I need to insulate the area between two heat sinks. The gap is about 10mm, and the bottoms of the heat sinks are facing each other with a peltier chip sandwiched in-between. However the two sinks are in separate enclosed sections, and I need to insulate the hot side from the cold side as much as...

Anyone know any good sources to read about Euler substitutions from? Both online and books would be suffice. Also videos, if there are any. All help would be greatly appreciated =)

Hello, on my robot I essentially have two sources of power. #1. The first is my 9-volt battery to the BS2. (+ pin 24, - pin 23) #2. my second is a power source for the motors. it uses four C batteries not directly connected to the stamp but with it's own system of circuitry. check...