Sources Definition and 538 Threads

A tertiary source is an index or textual consolidation of primary and secondary sources. Some tertiary sources can be used as an aid to find other sources. The exact definition of tertiary varies by academic field.
Academic research standards generally do not accept tertiary sources as citations.

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  1. J

    C/C++ Are there any good sources for learning Java as an experienced C++ programmer?

    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...
  2. F

    Finding Primary Sources for Physics, Chemistry & Mathematics

    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...
  3. S

    Solving Ideal Op Amp Circuits with Power Sources

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

    Uncovering Reliable Sources on Company Cultures, Especially in Tech

    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...
  5. B

    What Are the Best Foods to Eat Before an Exam?

    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:
  6. N

    Thin ceramic plates sources / manufacture techniques?

    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...
  7. N

    Euler substitution (Good sources)

    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 =)
  8. M

    Can I use one switch for two power sources on my robot?

    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...
  9. Femme_physics

    Parallel voltage sources circuit

    http://img297.imageshack.us/img297/7053/96217079.jpg given this circuit find the current on R1,R2 and R3. My attemptFirst of, I want to know-- did I build the equations correctly? http://img824.imageshack.us/img824/9804/mar1u.jpg [PLAIN]http://img713.imageshack.us/img713/213/mar2m.jpg
  10. Femme_physics

    Electronic parallel voltage sources exercises?

    I'm trying to google for some but results often lead me to forum questions, theory articles, etc. Basically I'm looking for circuits questions with parallel voltage sources answers, where I am supposed to do the work to find out the solution for the current.
  11. D

    Splitting a single light source into two out-of-phase sources?

    I've been contemplating an experiment on a 1-dimensional system which would require a single light source to be split into two separate sources which are exactly out of phase with each other. The idea is to focus the beams near each other (but not overlapping) along the 1D object. Any phonons...
  12. S

    Two point sources oscillating in phase- find smallest corresponding path length diff

    Homework Statement Two point sources S1 and S2, oscillating in phase send waves into the air at the same wavelength 1.98m. Given that there is a nodal point where the two waves overlap, find the smallest correspondign path length difference. The only given i can obtain form this is the...
  13. K

    Sources of information on time-frequency domain transformation

    Hello PF members I am a very new member to your forum and very new to time-frequency transformation. Over the summer I will be doing some research on vibration signals and for now I want to start understanding some basic things upon the time and frequency domain and transformation...
  14. K

    Sources of EM radiation in organisms?

    Organisms radiation EM energy. I am aware of the brain and nervous system as a source (because of electrical currents, etc) and that we have a lot of IR radiation. Is the majority of the energy due to blackbody radiation, a by-product of chemical reactions, or something else?
  15. B

    Engineering First order circuit with DC sources

    The circuit is in the attachment, plus the values that I've managed to find out so far. Im having problem with figuring out the voltage at t=infinity. So far i know that when t->infinity that inductors become short circuit. It says to apply current division and then Ohm's Law as a hint, and...
  16. N

    Sources Of Error: closed air column

    I did an experiment in class to determine the speed of sound. I used the speed of sound in air equation with the room temp at 28°C which was calculated at 348.6m/s. However when doing the experiment I got 329m/s. I just want to know some source of error that may have caused this? I have...
  17. S

    Why are most electrical sources, voltage sources?

    On wikipedia: http://en.wikipedia.org/wiki/Current_source Under the heading, "Current and voltage source comparison" It says that most sources of electrical energy are best modeled as voltage sources, that is supplying constant voltage. But why do most sources provide constant voltage...
  18. E

    Uncovering the Mystery of Fatigue Cracks: Sources, Detection & Prevention

    what are fatigue cracks? what are the major sources of fatigue withing the fuselage? how can fatigue cracks be detected during inspection? how can the risk of fatigue cracks in the fuselage be reduced? why are they dangerous? what is their origin? I've tried to find answers for these...
  19. K

    Sources of error for speed of sound lab

    Hi! Last Week we did a Physics lab on Speed of Sound. Two wooden sticks were banged against each other at a distance of 100 m from the wall(Then we went to 200 m, 300m and finally 400m) and the echo was heard and time was measured using a stopwatch. It was a rainy day. Can anybody suggest me...
  20. S

    Electromagnetic waves and charge sources

    Hi PF Are there an interaction between an electromagnetic wave and a charge source? For example, does an electromagnetic wave get attracted by a charge source, the same way the Earth attracts the moon? Or is something else going on?
  21. F

    Identifying Decay Heat Sources in Reactors Post-Trip

    I am looking for some data that identifies the most significant source of decay heat for the first few days from a reactor trip. Something similar for 1month after or more would be useful. Thanks Dave
  22. B

    Difference in current to load with series/parallel sources

    I feel this is a very simple question, but I can't seem to wrap my head around it. For example, if you have two 1.5 volt batteries in series and a load of 100 ohms then the total voltage is 3 volts and the current is 30mA because I=V/R. If you have two 1.5 volt batteries in parallel then the...
  23. I

    Beat frequency, find intensity at distance from sources?

    Homework Statement Three sources are emitting sound at 0.8W, one at 200 Hz, second one at 201 Hz and third one at 202 Hz. The sound travels in a shape of a half sphere. Find the intensity at 3m distance from the source (the sources are said to be very close to each other so I guess they can be...
  24. Saladsamurai

    Supermeshes and Dependent Current Sources: Determining the Constraint EQ

    Homework Statement I am doing some review and I though that I had this down pat, but I am getting confused a little. I am looking at the Wikipedia on Mesh Analysis. I do not understand the last equation of each section. How are they getting the signs of the currents? In the top image...
  25. P

    When will IceCube discover neutrino point sources?

    I understand that no such discoveries have been made. But there must be some astrophysics models which predict the abundance of neutrino sources. If there are such models, what are the odds that IceCube spot a neutrino source, after several years of operation?
  26. D

    Infinite Point Sources of Sound & The Zeta Function

    Homework Statement An infinite number of incoherent sources of sound are located on the x-axis at positions given by n2 (in meters) with n= 1,2,3,4,5... If all the sources emit with a power of 10.0W, calculate the sound level of the total sound wave at the origin. Prove your answer using the...
  27. S

    Exploring Ideal Voltage and Current Sources

    Homework Statement Homework Equations Is 1 an ideal voltage source? Is 2 and ideal current source? i was solving a noninverting amplifier circuit and i was asked to find out output impedence. and in the first circuit output voltage was independent of the load resistence => output...
  28. B

    Nodal Analysis w/ Controlled Sources

    Homework Statement Find V1, V2 and V3. Homework Equations Nodal Analysis Supernode Equation Capacitance = 1/R KCL & KVL The Attempt at a Solution KCL @ node 0: Ic = v2(-G1) +v3(-G3) Node 1: Ic + I1 +v3(G2+G3) +V2(-G3) = 0 (subbing in Ic) v2(G1+G3) + v3(g-3) = I1....Equation (1) Node 2...
  29. K

    Exploring Energy Sources for a Refuge in an Expanding Universe

    Dear All As I have understood, there will be only cooling chunks of matter like stray planets, neutron stars, brown dwarves and all other kind of debris left of our Universe in 10^20 years, which continue drifting apart as the Universe expands on (let us assume that it does). They will...
  30. J

    Current Sources in Superposition Theorem

    Why do we replace current sources with open circuits when using the Superposition Theorem while we replace batteries with wire?
  31. fluidistic

    Vector field, vortex free and sources free

    Homework Statement I must determine whether the following vector fields have sources or vortices. 1)\vec A = (\vec x )\frac{\vec a \times \vec x}{r^3} where \vec a is constant and r=||\vec x||. 2)\vec B (\vec x )= \frac{\vec a}{r+ \beta} where \vec a and r are the same as part 1) and \beta >0...
  32. F

    Interference of Waves: Two Point Sources in a Ripple Tank

    Homework Statement Two point sources in a ripple tank are generating waves with the same wavelength \lambda. They are placed a distance apart d = 5.5\lambda: --------------------------- | | | * | | ^ | |...
  33. D

    Calculating Current Through a Resistor Using Short Circuit Method

    Homework Statement Find the current through the resistor R1. The Attempt at a Solution First I short circuited the voltage source and determined I1. I1=(9A)(10-olms/18-olms)=5 A down Next, I short circuited the current source and determined the current going through R1 via olms...
  34. H

    What is the functional iW[J] for a system with 2 sources or 3 sources?

    Hello! I have a hard time getting to know what this exponential W(J) really is about. What is it even called? Zee writes: Z(J) = Z(J=0) * e^(i W(J)), and I suppose that this is the term that should be evaluated by summing over all possible pair of sources? What is W(J) for a system with 2...
  35. R

    Sources for the diffracted waves

    For diffraction you can assume slits in screens contain sources for the diffracted waves. But for a slit of finite width, how far apart are the sources? If the sources are continuously placed in the gap, then that means there are an infinite number of sources. An infinite number of sources...
  36. W

    Calculating SAR from multiple sources

    The Specific Absorption Rate (the rate at which energy is absorbed by a unit mass) given in W/kg is calculated by the following equation SAR = (sigma * Erms^2) / p Where sigma is the conductivity of the material (given in S/m), Erms is the RMS electric field (V/m) at the location and p is...
  37. F

    Multiple Energy Sources - Analytical Solution

    Guys, I was wondering if any of you has encountered a problem with multiple energy sources and the analytical solution for that problem. Is there any way to formulate this problem "without" superposition? Thanks, Frank
  38. W

    Adding power flux densities from multiple sources

    The Power density (Pd in W/m^2) at a distance r (in meters) for a transmitting antenna with gain Gt is given by: Pd = ( Pt * Gt) / 4 * Pi * r^2 where Pt (in Watts) is the power transmitted from the antenna. All these variables are scalar values so if there were multiple antennas and...
  39. M

    Two light sources against a wall

    Homework Statement Two light sources half a millimetre apart with a wavelength of 550nm shine on a wall exactly 50cm away. What is the distance between the centre point on the wall and the 10th bright spot out? Homework Equations x=nLv/d The Attempt at a Solution...
  40. E

    Transfer Characteristics of Real and Ideal Diodes (and more sources)

    I'm looking for information regarding the "Transfer Characteristics of Real and Ideal Diodes". I've tried google and the section on this site for learning material, but I've failed to find a site that displays both transfer characteristics and explains them. I was hoping that someone would have...
  41. P

    Sources of Electric Field inside a conducting wire.

    Suppose that we have a wire that connects the two poles of a DC battery. The current produced indicates the presence of some Electric Field within the wire, having a constant magnitude and a direction that follows its path. Now the question is : What is the source of that Electric Field...
  42. D

    Optics question - laser power sources

    We have a 532 nm laser that we use with our Raman tool. The only power indicator on the control is in the form of a percentage. I know that at 100%, the laser has a power of 25 mW. Does this scale linearly with power percentage? In other words, does 50% power translate to 12.5 mW?
  43. M

    Most power gravitational wave sources

    In reality what do you expect to be the first detection with GW detectors? Closest pulsars?
  44. Rasalhague

    Sources of Gravity: Exploring the Dependence of g_{\mu\nu}

    Is the following correct? In Newton's theory, gravity is a force (described in terms of a scalar potential field and its gradient), and the source of gravity is mass. In Einstein's theory, gravity is curvature of spacetime (described by the Riemann curvature tensor), R_{\alpha\beta\gamma\delta}...
  45. H

    How do I input a dependent current source in PSpice 9.2?

    Hello, I was wondering how to change the values of a dependent source in PSpice 9.2. For example, say I have a dependent current source that depends on the current flowing through some resistor and say that the current flowing through this dependent source is 2I. How do I input that into...
  46. A

    How Can a Backup Generator Automatically Support Two Different 3-Phase Grids?

    we are planning to install one backup generator to secure two differenr grids 3 phase each. how shall be the connection that gurantee if any source of the two grids is off, the generator will automatically start up and take the load??
  47. A

    Simple Electron Guns - Sources & Vacuum Storage Solutions

    Does anyone know of a good source for small electron guns? Just a simple one. I was using a TV CRT gun but the filaments don't last when exposed to atmosphere. I obviously operate under vacuum but I have no way to store my device in a vacuum for a long period.
  48. nomadreid

    What are the Three Sources of Red-Shift in Astronomical Observations?

    There appears to be three sources of red-shift: or are there only two, and two of the following are equivalent? (1) Classical Doppler shift (2) Relativistic Doppler shift (3) Red-shifting from the expansion of space Otherwise put, which ones are calculated for retreating galaxy clusters and...
  49. M

    Design Current Sources w/ DC Supply & Resistor/Transistor

    Homework Statement a) Design a current source using a simple DC power supply and a single large resistor. Assume you want to supply loads which can vary between 1 k and 10 k and you want the current to stay within 5% of 1 mA. b) Do the same thing using 2 DC power supplies and 1 NPN...
  50. A

    Power of Ideal Voltage Sources: Is it Infinite?

    hello, in my course I read about ideal sources - an ideal voltage source holds a constant voltage , no matter the currect it's giving so can I conclude that those types of sources has an infinite power in itself ? (power = voltage x current) maybay a stupid question... thank you
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