Source Definition and 1000 Threads

Since friction is a "force" and is able to stop a moving object, why doesn't it possesses energy? For example, light, which is an electromagnetic wave, is emitted from a source which have the energy to "do light". Then what is the source of friction? An object cannot just intrinsically...

Homework Statement Homework Equations P = 1/2 Vm*Im*cos(θv - θi) The Attempt at a Solution First I added all the impedance values to find the total impedance seen by the source. Zt = j10 + (50 || 20 + j10) = 15 +j5 Ω Now since the circuit is not purely resistive, I can't...

Homework Statement A typical incandescent light bulb emits ~3x10^18 visible-light photons per second. Your eye, when it is fully dark adapted, can barely see the light from an incandescent light bulb 10 km away. How many photons per second are incident at the image point on your retina...

Is a resistor a voltage-controlled current source? WHY? I think it is but I don't know whether I'm correct.

Hi everyone, As I was doing some research on nuclear energy moratorium, I came across the Bulletin of the Atomic Scientists Journal . After reading some of their articles, I realized that they have a very negative view on nuclear energy. I do not completely trust the source but I would like...

Homework Statement Homework Equations The Attempt at a Solution First, I found all the impedance values. (starting from the left) Z1 = 1 / (j * 16E5 * 15E-9) = -j41.67 Z2 = 80 Z3 = 30 Z4 = j * 16E5 * 60E-6 = j96 I then combined Z1 and Z2. Z1 || Z2 = (-j41.67 * 80) /...

I was having trouble while thinking about the unreal source for refreaction through a lense... In lense light is refracted twice...the real image for the first refraction works as an unreal source for the second refraction... I understand how it is... But fail to feel it... I mean how would I...

Homework Statement http://www.mediafire.com/view/?3efd7326e49kteb I've worked out all except part (iv). These are my workings : http://www.mediafire.com/view/?elswc5g5412zhzq I just can't see how to get rid of cos(pi*(x1+x2/λ -wt). Also, where does the I0 come from ?

Homework Statement http://www.mediafire.com/view/?09c89b8986u5zls The above is a question from my problem sheet. I've got no idea how to attack this since its been very poorly explained in my lecture handouts. Can someone please help me ?

Homework Statement If an average power of 500W is dissipated in the 20Ω resistor, find Vrms, I S RMS, the power factor seen by the source, and the magnitude of VS (Based on circuit in attached diagram) Homework Equations Pave= Irms*Vrms*pf*\frac{1}{2} Imaginary number referred to as...

In the paper "A Mathematical theory of Communication" by Shannon I couldn't understand a theorem (Theorem 4) under the topic "The Entropy of Information Source"- Here 'H' is the entropy. Can you explain me how we get this theorem? What is this n(q)? I couldn't understand the sentence...

hello, in MTW Ex 19.1, it was considered a Weakly gravitating body whereas in Ex 19.3, a Stationary relativistic source. What relativistic means here ? does it mean the source is very dense and massive ? or does it mean it is rotating at near the speed of light ? Can I specify the mass as the...

Hi all, Is it possible to find the direction of a source in 4 quadrants using directional antenna? I am thinking of setting up 4 directional antennas, facing to 4 quadrants, and they will receive the waves from the according quadrants. What do you guys think about this? And is there any...

An electron and a positron annihilate and energy is released in the form of quantized EM (gamma etc.) rays: Now some childish yet inquisitive questions; 1. Where were there quanta prior to annihilation, inside the electron or positron (or both)? 2. Were these quanta really present...

Hi guys. I am having some issue and would love any help. I have a project that requires 30 motors to be hooked up to a single power source. The problem is, the surge voltage that happens the moment the motor turns on causes the buildings circuit breaker to trip. The only way to bypass this...

iam using atmega 32 and i want to use external 16MHZ crystal I have figured out the fuse setting for this as lowbuyte=0xFF and highbyte=0Xc9 what i cannot understand is should i set fuse bits before programming or after programming? because as i have specified external crystal as clock source...

I have an unidentified radiation source. I used a NaI(Tl) detector and multichannel analyzer to collect data and plotted the spectrum. I found peaks at energies of 86.3, 123.7, and 369.6 keV. From this data I am attempting to identify the source, but I am having a difficult time. I tried using...

Is MinutePhysics (youtube) a reliable source? I've been watching his videos since they started, but some of the stuff he mentions I question, or is Physics so amazing that I can't believe it xD?

Hello, for the Poisson problem Δu = -1 on a 2D circular disk with u = 0 on the boundary, we have average(u) = \frac{1}{8\pi}Area(disk), which is easy to see, as the solution is quadratic in the polar coordinate r. Does this (or a similar) relation hold for non-circular 2D domains? This...

Homework Statement I uploaded the assignment it is problem 2 Homework Equations The Attempt at a Solution I really just want confirmation that my work is ok, and the command for a dependent current source in PSpice. The things that I found that are dependent, are very confusing...

FIRST OFF: Sorry for the multiple post on this subject, I couldn't figure out how to edit my first post on this topic (I promise I'm not spamming!) Homework Statement Homework Equations The Attempt at a Solution Step 1: Removed unnecessary resistors R1 and R3. R1 is removed...

I was just wondering if a person wearing convex lenses looks at a light source... Will excess heat be generated in his eyes? As it is a converging lens.. Thanks!

I'm Rich! "New Energy Source"! Tonight I found a very professional looking, 200+ page report lying on my back doorstep. It was a in a folder titled, "New Energy Source", and included the name, phone number, and email address of the person responsible. I have no idea who this person is, why they...

I have an idea for an experiment to see how the distribution of photons changes when they are emitted from a moving photon source. This is a continuation of an earlier discussion here with added information and more questions. "What happens to a photon wave packet when half out of a moving...

Hey everyone! I am designing an experimental, manned aircraft that uses twin caged propellors for VTOL, and I'm looking for a lightweight, high-output power source to power them. Any ideas?

I'm trying to understand the nature of the virtual particles that exists in empty space. I understand that they 'bubble' in and out of existence, but why do they exist in the vacuum of space? If all particles spend some of their time as virtual particles, does quantum mechanics suggest that some...

Homework Statement http://imageshack.us/a/img834/5512/homeworkprobsg216.jpg Using superposition, find i.Homework Equations V = IR, KVL, KCL, Nodal / Mesh analysis, voltage division, current divisionSuperposition procedureThe Attempt at a Solution So this time the dependent source is a...

Homework Statement Find i1 in the following figure, given: Vs=10V, I=1A, R1=5, R2=2, R3=4 Homework Equations KVL The Attempt at a Solution Applying KVL to mesh 1: Vs-i1R1-(i1-i2)R3=0 and i2=I=1A So, i1=(Vs+i2R3)/(R1+R3)=(10+1*4)/(5+4)=14/9=1.56 A But book gives answer as...

Homework Statement http://imageshack.us/a/img831/2617/homeworkprobsg213.jpg Find the load RL that will result in maximum power delivered to the load of the circuit. Also determine Pmax deliveredHomework Equations V = IR, KVL, KCL, voltage division, current division Thevenin procedures,Pmax...

Hey Folks Quick disclaimer: I have no background in physics whatsoever but I have found myself trying to solve a problem that is seemingly based in physics so I am trying to learn. I also have a background in search and search engine optimisation which usually means I am a dab hand at...

Homework Statement five branches left most branch: 50 Volt source second left most: 10 ohm resistor shared branch between the second left most branch and center: 10 ohms (Voltage drop from left to right= V delta) center branch: 30 ohm resistor between center and second right...

Homework Statement http://imageshack.us/a/img15/7218/sg2prob11.jpg Find the Thevenin resistance for the network(Sorry for the bad drawing, but that is a point like point / node A on the bottom where it's going out too and likely part of the load too, with a wire connected to the circuit, I'll...

Homework Statement Please help me to solve this type of circuits... I want to find the intensity through each power source and what voltage does the voltmeter indicates. http://iceimg.com/i/f5/1d/2da68fc0a6.png Homework Equations I=I1+I2 The Attempt at a Solution don't know

I want to get some opinions on what the source of dark energy is? I think there are basically two camps here. One camp says that dark energy originates from space itself, it is some perturbation in the quantum field whereby one cubic meter of space becomes 10 cubic meters somehow, and so on...

Homework Statement http://imageshack.us/a/img26/8403/homeworkprobsg28.jpg a. Use source transformations to find the voltage V0 in the circuit (green). b. Find the power developed by the 250V voltage source c. Find the power developed by the 8A current sourceHomework Equations V = IR KVL...

Homework Statement 3 branches, Indpendents are a 15 Volt source (left most branch) in series with a 2 ohm resistor (current that flows from left to right though this resistor is 'i delta'), Middle branch contains a 5 ohm resistor in series with a current controlled voltage source (3 ohms * i...

Do any of you look at source codes from websites, do you write source codes?

Greetings to all, I know activity for a Am-Be neutron source. I want to compute strenght source in neutrons/s. Yours advices are welcome. Thank you!

Homework Statement By integrating (2-55), over a small volume containing the origin, substituting ψ = Ce-jβr/r, and letting r approach zero, show that C = 1/4π, thus proving (2-58). Homework Equations (2-55): ∇2ψ + β2ψ = -δ(x)δ(y)δ(z) (2-58): ψ = e-jβr/(4πr) The Attempt at a...

Homework Statement By integrating (2-55), over a small volume containing the origin, substituting ψ = Ce-jβr/r, and letting r approach zero, show that C = 1/4π, thus proving (2-58). Homework Equations (2-55): ∇2ψ + β2ψ = -δ(x)δ(y)δ(z) (2-58): ψ = e-jβr/(4πr) The Attempt at a...

Hello all, I'm having a bit of a difficult time following a specific conversation that I had with one of my professors. Occasionally, we would be given a 3-phase load (balanced or unbalanced), with merely the wires shown (the formation of the sources was not revealed. See the image below. I...

Homework Statement Design a circuit based on the noninverting op-amp configuration that functions as a 1mA ac current source. Homework Equations Gain = Vout/Vin = 1 + R2/R1 The Attempt at a Solution I really don't know how to start.

Homework Statement http://imageshack.us/a/img26/4592/homeworkprintprob.jpg Find the voltage V0 in the network.Homework Equations V = IR Voltage Division: (Voltage across series resistor) = [(resistance) / total series resistance)](total input V) Current Division (for 2 parallel resistors)...

I'm trying to get a better understanding on how grounding, bonding, and earthing works when high voltage sources interact with lower ones. For example, if you have a 400V AC, 20V AC, and 5V DC source all stored in the same aluminum cabinet (surrounded by a faraday's cage and connected to earth)...

I need some kind of environment in Latex where you can write whatever you want without it interpreting it. The reason is I need to include a MATLAB code. Most places I go says I have to use the lstlisting environment, but that doesn't work. Or at least I get this error: ! Package inputenc...

[b]1. Explain what the CPU will do in terms of functuality and configuration when executing the C source code below: unsigned char value = 0x91 1) BSR = 5; 2) BSRbits.3 = 1; 3) INTCONbitsTMR0IE = 1; 4) INTCON2bitsTMR0IP = 1; 5) TRISB = 0x00; 6) PORTB = 0x00; Please can...

Is all motion basically the result of big bang, including atomic and sub-atomic motion?

Hello Physics Enthusiasts The other day I received in the mail a uranium ore sample from United Nuclear, with a radiation measurement of 2,500cpm, intending to use it as a particle source for my replication of the famous Gold-Foil experiment, the theory for which was devised by Ernest...

Homework Statement I had an assignment where I needed to calculate reaction rate constants at different temperatures. I was supposed to use ab initio method (meaning I should use Spartan software), molecular partition functions and Eyring equation. The reaction was: H+HD...

Greetings fellow members!(New guy!) Before I would start, I've already read a lot of the threads related to "magnets" and "energy". I do undertand the PF forums rules. So please don't lock this thread and say "THIS IS NOT ALLOWED" in reality it is... But maybe its because of the unfortunate...