# What is Sources: Definition and 537 Discussions

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. ### Addressing Source Credibility and Clarifying Guidelines for Engineering

Just noticed (as a follow up of a recently terminated one) that many topics posted in 'Engineering' actually does not conform with the general rule about respectable sources, causing confusion. Sure, engineering has a way to say 'see? Works.' and it's totally (!) respected in the actual attitude...
2. ### I need sources to learn about dynamic systems

Hi! I have exam in couple of weeks , and now am looking for sources to learn about dynamic systems , chaotic systems and etc. My main goal is to learn characteristics of such systems , learn about special points in dynamic plane. For the most part we used to create dynamic system simulations...
3. ### 3d plot of interference from 2 wave sources with 2d grid surface

Desired output similar to image, but without the objects and with better wave interference: I tried plugging the following into wolfram (I specifically want the values to be adjustable): plot z= H*e^(-m*sqrt((x-a)^2+(y-b)^2))*sin(k*(x-a)+k*(y-b) -w*t) +...
4. ### I Research paper and sources investigating Earth's moons

Hi. I am looking for scientific papers, articles and/or even simulations that investigate how many moons it would be possible for earth to have and maybe modern theories about what these moons can be and look like (i.e what characteristics they have) if they were to exist. I have googled and...
5. ### Rectifier circuit for AC sources with 180˚ phase offset

In a simple 2-phase generator that I am making, I have 2 pairs of oppositely placed copper coils in arrangement similar to this: I would like the generator to power DC devices. My question is: How could one rectify the output from opposing coils? Or, in other words, how could you rectify 2 AC...
6. ### Comp Sci MVC Architecture different in different sources

Source: https://www.chromeinfotech.net/blog/model-view-controller-architecture/ Source: University of Virginia Computer Science, Engineering Department youtube lecture. Here're my 2 questions: 1) Does user interacts first with a view or controller? 2) Does model sends output directly to view...
7. ### Nodal analysis of this circuit with 2 sources and 4 resistors

Here is the question a. Plot nodes in the problem and indicate how many equations will be obtained. answer: two unknown variables b. Use node analysis. Derive the system of equations for the voltages in the circuit. question: Did I calculate right V_a and V_b? C. Calculate the...
8. ### A How making the ions leave the cavity in a ion sources

Ion sources are devices that allow creating ion beams (e.g. argon ions) and to project them outside the device, for example to be further processed by a particle accelerator, or to irradiate materials or biological tissues etc. The ions are usually created by a plasma inside a cavity filled...
9. ### Sources of voltage ripple in buck converter

I am reading a book 'Fundamentals of Power Electronics' - Erickson. The book begins with a buck converter and the assumptions that we use so that we do not have to deal with 2nd order equations. I will first explain what the book says What the book says? The book says that the LC filter of a...
10. ### Looking for information on gamma light sources

Hello, I am looking for something a bit out of my wheelhouse today, gamma light sources (10 MeV or higher on the max energy threshold). Does anyone here have experience or more information on these machines? Are they typically electron accelerators utilizing a tungsten or tantalum target? I am...
11. ### I Gravitoelectromagnetism: Why Equation Differs in Sources

In article "A note on the gravitoelectromagnetic analogy" by Matteo Luca Ruggiero (https://arxiv.org/pdf/2111.09008v1.pdf) equation number 18 is ##\nabla \dot\ E=4 \pi G \rho## , but corresponding equation in the wikipediapage(https://en.wikipedia.org/wiki/Gravitoelectromagnetism#Equations) is...
12. ### Data sources for Vehicle Dynamics Model validation?

Hello all, I have written a VDM for my Masters thesis, unfortunately, since I am from a discipline other than mechanical engineering I don't have access to reliable validation material or a way to produce it (moreover, we don't have an actual vehicle testing lab/area at the U that I know of)...
13. ### I Energy emitted by EM sources under constructive interference

I'm trying to wrap my head around the energy increment under constructive interference. In short, why does energy increase quadratically when each source emit EM wave that interferes constructively? Suppose we have an array of identical and equidistant sources, each of which span the entire x-y...

15. ### Superposition Principle for two Voltage Sources (confusions about....)

I have a question about natural limitations when the superposition principle for circuits is applicable. Possibly there is a quite elementary reason why the problem I'm going to present next fails, but up to now I haven't a precise reason why that's exactly the case. Could somebody help...
16. ### Quantum Readable sources for C*-algebras and GNS construction?

It is there a gentle introduction to C*-algebras and the GNS construction that is readable for physicists? You know, a text with an emphasis on QM that is formal enough to not be sloppy but not too much as to require a Ph.D in functional analysis to be read.
17. ### I Entropy change due to heat transfer between sources

Hi, starting for this thread Question about entropy change in a reservoir consider the spontaneous irreversible process of heat transfer from a source ##A## at temperature ##T_h## to another source ##B## at temperature ##T_c## (##T_h > T_c##). The thermodynamic 'system' is defined from sources...
18. ### I Any other good sources on the Lamb shift other than Wikipedia?

Title says it all :)
19. ### Two observers viewed from different sources

I builded the translated lorentz transform, at t=0 t'=-22.5 and x'(x=0)=67.5 after that I just didn't the question
20. ### Data Sources for Vaccination and Covid-19 cases by Age

Is there an up to data source of data on the number of vaccines administered in the US by age and sex? And similarly is there up to date information on the number of Covid-19 cases by age and sex, as well as number of adverse events from Covid-19 infection?
21. ### Reliability of Sources: Questioning & Rejecting

I seen on another site where a user called out the site moderators for ignoring facts of science from a previous thread. They used what appeared to be reliable sources that went against the site moderators. What got my curiosity level up is how the thread was closed quickly by the moderator...
22. ### A Looking for sources of information on Black Holes

hey Im new here, I am a masters degree student. I woud ask about any good source for understanding black hole for a master's degree student. thanks
23. ### Background radiation sources question

Several sources of background radiation include; Radon gas from soil, rocks and building minerals; since radon is produced by the decay of uranium ore present in certain rocks e.g. granite. On Earth, approximately 42-51% of background radiation is the result of naturally radioactive gases like...
24. ### Fusion reactors are neutron sources AKA fission bomb factories?

Assumptions: 1) Fusion reactors are easily obtainable. Every spacecraft or hover-car has one. 2) Fusion reactors are neutron sources. 3) Neutron sources are the "difficult bit" in the enrichment of uranium and plutonium. 4) Uranium and plutonium are "freely" available in asteroids or...
25. ### RLC Circuit Analysis -- Two sources and two switches

Hello, this is my working. My professor did not give any answer key, and thus can I check if I approach the question correctly, and also check if my answer is correct at the same time. When t < 0, capacitor acts as open circuit, $$V(0-) = V(0+) = 9V$$ When t = infinity, $$V( ∞) = 5V$$ (because...
26. ### Finding second furthest distance of const interference from 2 sources

So I can find the wavelength using v/f = 0.8995. for the distances, d=x and d=sqrt(9.7^2+x^2). So the full equation would be sqrt(9.7^2+x^2)-x=n(0.8995) Now I am going to take the derivative of the left side to see where the maxima is. 0= sqrt(x2+9409/100)−x Now this doesn't have a solution...
27. ### Circuit problem with two sources and three resistors (Nodal Analysis)

Ans: 0.123A Tried mesh analysis and got it but didnt for nodal analysis
28. ### Basic NMOS+Zener Current Source Test

I have been trying for a long time to build a costant current source which I know is impossible to keep the current exactly the same but as much as possible. This is what I have done so far: The operation is very simple . If VCC is increased the VAC is increased a little bit. When VA is...
29. ### Engineering Determining if voltage or current is positive or negative with sources

So I'm confused on a few things about this circuit. I know my math is right (since I got the absolute values correct), but the signs are off since I can't tell when the voltage, current or if the general power equation is positive or negative. A) So my first question is, where is the current...
30. ### Engineering Step response of RC circuit with independent voltage and current sources

Dear PF, In the figure down below is Q7.47 which asks to determine the voltage v(t) across the capacitor for t > 0. Since it is given that V(0) = 0 there are two scenario's which is between time interval 0 < t < 1 and t > 1 according to the independent sources. For the scenario 0 < t < 1 the...
31. ### Can Two RF Signal Sources Connected in Parallel Increase Signal Amplitude?

Suppose I connect two identical signal generators to a dividing coaxial cable with two input ends and one output end. Is the signal amplitude from the output end the same as from one source, is it twice that or something in between? If this should be seen as analogous to two DC voltage sources...
32. ### The sources of error in a diffraction grating experiment

In a diffraction grating experiment, what can be the sources of error and also what effect do these sources have on the unknown quantity (wavelength) in the experiment?
33. ### A Crystallographic representation of a material, two sources seem very d

While searching for a software to plot a crystallographic representation of a particular material, I have come across two sources that seem to give two very different views of a same material. In this case, it is CoSb3. On the one hand there is from ASE (Atomic Simulation Environment), a...
34. ### Using Kirchhoff's Laws to Solve this Circuit with Voltage and Current Sources

I have defined 5 currents but I can't seem to solve it. I1+1=I2 (left) I5+1=I4 (right) I2+I4=I3 upper node By KVL I have determined that I2 and I4 are equal, but I cannot determine the specific current across each resistor. Thank you for your valuable help.
35. ### Two light sources are a distance D apart

I let E1 be the event where source 1 emits the photon and E2 for the second source with the respective coordinates in O as $(x_1, t_1$) and $(x_2,t_2)$ such that $t_2=t_1 \because$ simultaneous and $x_2-x_1 =D$. Using Lorentz transformation I obtained that in O', x'_2-x'_1 = \gamma...
36. ### Why can't two laser beams from two sources Interfere if they have a difference phase?

I read in the internet that the reason that two laser can't Interference because they most likely have difference phase. but electromagnetic wave are just change in the electromagnetic filed that goes up and down , so mathematically they may Interference little let say that the there is...
37. ### Can we connect two laser sources to make a stronger beam with a larger radius?

there is anything that have input of two laser and output one laser with a bit bigger radios or just stronger laser like a beam just the opposite instead of splitting one sources connect two sources
38. ### Material Models Sources: Ludwik, Holomon, Swift, Wok, etc.

Who can share the primary sources where material models are formulated: Ludwik, Holomon, Swift, Wok, Ludwikson, Hill and others?
39. ### Other What are some sources of recommendations for Math books?

I'm a lover of books about Mathematics. However, I have noticed it's quite hard to stay in touch with new releases or book reviews in the world of Mathematics. I use GoodReads for recommendations in most genres of Fiction and it does a good job, but it very rarely covers or recommends new books...
40. ### Geiger Counter and ultraviolet light sources

I purchased a RadiationD-v1.1(Cajoe) geiger counter off ebay, and attached an arduino nano and a 16x2 display ( I got the instructions off this site https://www.instructables.com/id/Arduino-DIY-Geiger-Counter/). I noticed that the counter was sensitive to UV when I had it out in the sunlight, so...
41. ### Radiation heat transfer using 12 heat sources

The intensity is proportional to the square of the distance between the source and the body and also depends on the angle of incident. I = The intensity at 0° (Assuming I = some constant) then I0 = I cos(Theta) Theta = the angle of incidence. I want to solve this using trignomentry. Is it...
42. ### Circuit Analysis Question -- 2 sources and 4 resistors

Now, I know this question can be solved using Kirchoff Voltage rule, but the question expliciitly wants me to use power supplied = power absorbed. Hence taking V0 to be x, I can't still seem to calculate. Any ideas? Power supplied = (60)(3) + (5x)(3) = 180+15x Power absorbed = 72+ 56 +28 + 3x...
43. ### How to calculate the entropy for two sources

Hello to everyone, I'm studying thermodinamics and I would like to understand better the meaning of entropy and how to calculate it. I know that if A and B are two possible states of a system, the equation whcih defines variation of entropy from A to B is...
44. E

### B Confused about the need for passive sign conventions in sources

For passive electrical components, I can understand the need for the passive sign convention - i.e. taking the voltage to be the potential on the side where the current enters (higher potential, for a passive component) minus the potential on the other side. For a resistor, this means the change...
45. ### Finding the currents in this circuit (2 voltage sources and 3 resistors)

In my attempt, I tried 1) I1 = I2 + I3 Then set up these two equations based on Kirchhoff's second rule: 2) U1 = R1 (I2) + R3 (I3) and 3) U1 + U2 = R1 (I1) + R2 (I3). From what we have 10 = 0.1* I_2 + 0.2 * I_3 22 = 0.1* I_2 + 0.02*I_3 I_3 = 50 - 0.5 I_2 That means I_2 = 233.3 A I_3 = -66.7A...
46. ### Optics (dealing with 2 sources of wavelength)

To start off, I dealt with questions similar to this, but it only involves one wavelength. Now that there's 2 wavelengths, I'm kind of stumped as to what I should do. Since the question stated a second dark fringe, I can assume that it will be a destructive interference. Since the rays are...
47. ### Best Raw Propellant Sources For A Scifi Spaceship

Rocketry is not good enough for the standard scifi spaceship that can take off and land like it pleases with high payloads. Yet I still like rocketry because I like the fiery exhaust plumes. So I am considering linking the spaceship's rocket engine to a portal linked to to a planetary...
48. ### I Best sources to understand the Wigner-Eckart theorem?

I have to admit that my understanding of the Wigner-Eckart is quite precarious. In my grad studies I try to learn it using Sakurai and I suspect that might have been the wrong choice. So, what books-articles better explain the Wigner-Eckart theorem?
49. ### Can Ohm's Law Be Defied with Independent Power Sources?

In my study of electrical engineering I have been told that the voltage across a resistance is V = IR. If I connect a resistor R and a power supply of 5V 2 A then how does ohms law work here? I could change R to anything I want but the source would stay at 5 V and 2 amps regardless of what I do...
50. ### How to find the current and voltage in a circuit with current sources?

Summary: Facing a circuit with 2 parallel resistors and 2 current sources (1 dependent, 1 independent). Trying to find the current, voltage, power delivered by the independent current source and power delivered by the dependent current source. I'm trying to start by finding the current i0 but...