What is Sources: Definition and 538 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. B

    Calculating physical separation of 2 sources at unknown angle.

    I am doing a small project on Gamma Ray Bursts. I am looking at a data set of around a dozen bursts which are observed at an angular offset from their host galaxies (My theory is that they are in dwarf galaxies orbiting the host galaxy). Say the average separation of these GRBs is 4...
  2. bibo_dvd

    A Question about Voltage Sources in Parallel

    Hello Guys ! My Question : in this photo i found That Total Resistance will be = 7 ohm . and I2 = 12 / 7= 1.71 A and I1 = 0.5 * I2= 0.5 * 1.71= 0.85 A I can't understand why I1= 0.5 I2 ?? and why it isn't the same of I2 ?? here is the photo Thank you Guys ! :))
  3. P

    AC Voltage Sources Riding A DC Voltage Source

    Hello again, I am having a bit of trouble understanding superimposed voltage. Here is the problem: A sinusoidal AC voltage source is in series with a DC source. Effectively, the two voltages are superimposed. Draw the total voltage across RL. Determine the maximum current through RL and the...
  4. P

    Doppler effect with 2 sound sources

    Homework Statement A fly is moving with a speed vl=3m/s and a bat is chasing it with vs=5m/s. The bat is emitting a sound with fs=50kHz. They are moving on the same line towards point C which is a source emitting a sound at f'=57Hz. Find the frequency of the total sound the fly is hearing. The...
  5. S

    Nodal Analysis problem with voltage sources

    Homework Statement I have a circuit and I need to find the Nodal Equations that would mathematically describe the circuit, then proceed to finding the voltages at each node using Cramers rule and the currents at nodes 2 and 4. I don't think I would have much of a problem utilising Cramers...
  6. G

    Engineering Can You Simplify a Circuit Node with Both Voltage and Current Sources?

    Homework Statement I've been struggling with simplifying this circuit, eliminating a bunch of sources and moving around stuff in general. I'm still very unsure of how to handle nodes with multiple sources though. Like in the picture I've attached. I've got a voltage source and a current...
  7. I

    Handling high voltage sources?

    Don't know which sub-forum this topic belongs to so I'm sticking it in here. I'm currently at a temp job testing hot melt machines that powers from a 240v 3 phase source. Electrical safety was never really emphasized in engineering school. Is there a standard list of safety protocols or 'do...
  8. P

    Generators - Voltage Sources or Current Sources?

    I am actually quite confused on how a generator is supposed to be modeled... To add more power to a bus, we put more generators in parallel at the same voltage (which is the bus voltage). Therefore, I would say generators are current sources as more generator are put in parallel, more current...
  9. A

    Double slit experiment with multiple sources of particles

    Im somewhat new to modern physics, had one introductory class in my university and because it fascinated me so much, I've watched all the leonard susskind lectures on quantum mechanics, entanglement, and particle physics on youtube on the Stanford channel. Today I noticed something strange...
  10. N

    Ladder problem (statics) with 2 sources of friction

    Homework Statement A uniform ladder of mass m and length L rests against the wall as shown. The coefficients of static friction between the floor and the ladder and between the wall and the ladder are equal to each other (μ). What is the maximum value of angle θ that the ladder can make with...
  11. S

    Engineering Circuit analysis with diodes and multiple current/voltage sources

    Homework Statement This isn't a homework question, just one I can't get the correct answer to. The circuit diagram is attached, and I need to find the voltage at V. The Attempt at a Solution Assume the voltage drop across each diode is 0.6V. Let V_5 be the voltage drop across the current...
  12. A

    Inductor and capacitor as current and voltage sources

    Hi, I have just seen this statement in another forum: An inductor is a constant current source for a limited time until its energy is expended. A capacitor is the counterpart being constant voltage until its energy is spent. I am not quite understand it. Can you help me? This is not a...
  13. P

    Where can I find resources to learn the math behind quantum mechanics?

    Hello all, I am an amateur "physicist" just tinkering and experimenting with my son, and as I read the posts about different concepts, I can get the general idea of what is being explained. However, when it comes to the math (equations for the wave functions, calculating eigenstates, etc.) I...
  14. E

    Can You Combine Current Sources Question

    http://imgur.com/09Rj0ND 2. V=IR 3. My real question is if I can combine the current sources. I'm pretty sure you cannot. I have combined the resistors in parallel, but I am not sure what to do next
  15. F

    Question about perception of colors around light sources

    When I look at a distant light source (like car headlights, or street lamp lights) I notice colors of the visible spectrum (as separated (as in after prism refraction)) immediately around it and it's not just around white light sources. It becomes more obvious if you place something with a...
  16. T

    Fluids: potential flow, calculating gauge pressure from two sources

    Homework Statement In a plane onset flow of 4 m/s, a source of strength 13 m2/s per metre is located at the origin (x=0, y=0) and another source of strength 18 m2/s per metre is located at (x=3m, y=0). Calculate the gauge pressure at the point (0, 2m), Take ρ =1.2kg/m3 Homework...
  17. E

    Sources of error in thermal expansion

    I was just wondering what would be sources of error in calculating thermal expansion
  18. X

    Can interferometers be built with multiple light sources?

    Hi, it's probably a stupid question, but I was wondering if it's possible to build interferometers with two perfectly calibrated lasers at the same wavelength. Would the same sort of results appear as with a single source of light, or does the fringe shifting effect only appear when the photons...
  19. D

    Superposition for dependent sources and Pspice

    Homework Statement The problem is uploaded it is problem number 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...
  20. R

    Simple circuit analysis w/ voltage sources - MasteringPhysics wrong?

    Homework Statement We are given a simple circuit with 4 resistors, a known voltage source, and an unknown voltage source. The photo is below in my solution attempt.Homework Equations V=IR, R(parallel)=(1/R1+1/R2)^-1The Attempt at a Solution I found the voltage drop over the given resistor, then...
  21. D

    The superposition theorem with dependent sources

    Homework Statement Use the superposition principle to determine the value of Ix. Homework Equations I1+I2+I3=0 KCL V1+V2+V3=0 KVL Ix'+Ix''= answer The Attempt at a Solution So I understand how to get Ix' its just standard KVL it is -10+2Ix'+Ix'+2Ix'=0 which solving for Ix' gives 2A...
  22. E

    Power transferred from the sources to the electromagnetic field

    Hello! In an electro-magnetic context, the power that an electric source of field delivers to the field itself may be written as p_S = - \mathbf{E} \cdot \mathbf{J} where \mathbf{E} is the electric field produced by the source and \mathbf{J} is the corrent flowing on the source, forced by...
  23. C

    Dependent source with 2 other sources (using superposition), mesh

    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...
  24. C

    Circuits with two voltage sources

    Homework Statement Well this is the problem: Whats the current in I1 and I2? Homework Equations I'm guessing you use Kirthoff's Laws.The Attempt at a Solution Well, what I did was I broke it up to two different circuits but then it would have two different currents flowing into the 2 ohms...
  25. M

    Why is it hard to discover new energy sources?

    Why is there a difficulty in the world to discover new energy sources? That is long lasting, eco-friendly, and highly efficient. We've progressed in many many fields but I find this field being the least... I've been thinking a lot about this, since in the future I'm specializing in this...
  26. A

    Why Don't We Invert the Signs of Voltage in Circuit Analysis?

    Homework Statement https://www.diigo.com/item/image/2sb3i/1svo Why don't we flip the signs of VA like this : https://www.diigo.com/item/image/2sb3i/g2a4 because the current must flow from + to - of the resistor. Homework Equations none The Attempt at a Solution none
  27. D

    Medical Good online sources for medical & health research

    I'm looking for a place online that lists and/or describes recent medical studies on various issues. For example, I've heard conflicting information on whether Omega 3 supplements (fish oil) can help prevent memory loss. Some studies have indicated yes, others no. What I'm looking for is a place...
  28. T

    Voltage Division with Multiple Voltage Sources Seperated by Resistors

    Homework Statement Find the voltage across the 10 ohm resistor. http://www.spacemonkeybrewing.com/images/circuit.jpg Homework Equations KVL - Sum of Voltages in a closed loop equal zero. Ohms - V=IR Voltage Divide - Va1 = (R1/(R1+R2...))Vs The Attempt at a Solution This is only...
  29. C

    Potential formulation of Electrodynamics with magnetic sources

    Hello! I am trying to construct (if it is possible) a potential formulation of an electromagnetic theory which permits the presence of magnetic sources, using as a starting point the equations referred here: http://en.wikipedia.org/wiki/Magnetic_monopole Although I think that I have make some...
  30. E

    Reactive power with electromagnetic sources in free space

    Good morning, in circuit theory I know that reacting power arise from phasors and represents a power which can't be used, because not delivered to any load, but continuously flows back and forth between the load and the generator with a zero mean during one period. I can't understand very well...
  31. C

    Current amplification without external sources

    i want to amplify my current from 300mA to 600mA. i m making a solar charger and the specifications say 6v 400mA. however i m unable to receive 400mA.. is there a way to amplify current to 600mA from 300mA.. i can lower my volt to 5V from 6V. i don't want to use any external dc or ac supply
  32. A

    In downconversion, can you get coherence between the signals from two sources?

    In the ZWM study of 1991 Mandel et al get coherence between the signal photons of two distinct downconversion sources. This is shown with an interference collection between the two possible sources of signal photons (even though they are entangled with the idler). This is achievable because...
  33. P

    Please advise the sources of finding sample question for semi&superconductors

    hi all, please advise any books or websites or any other resources that I could find some sample questions (like the sample exam questions) for those subjects (more questions the better! ideally with answers!) Really appreciate for your help! !
  34. A

    Question about the interference effect with two distinct sources.

    The optical two-source interference effect due to Hull (1949) has largely been overlooked by the history of quantum mechanics. Mandel and Fleegor brushed up the effect by reducing the signal strength of the sources and reducing exposure times for interference collection. In the end this effect...
  35. B

    Future Energy Sources & Weapon Systems Ideas

    Hi everyone. I have a few ideas floating in my head for a story I would like to write. I have got nothing concrete yet so my story is still very flexible. First of all the story will take place in the nearish future, say in 80-120 years. First of all, I want some ideas of possible power...
  36. jaumzaum

    Can 2 light sources of different wavelenghts interfere one in another?

    I'm asking because I was solving a double slit experiment problem in which the light was bichromatic (composed by 2 different colors, λ1 and λ2). What would we seen at the screen? Are there places where only one wavelenght is observed? Can the 2 wavelenghts interfere to create a third...
  37. dexterdev

    Algorithms and Sources of entropy for PRNG and TRNG?

    Hi PF, I would like to implement different random number generators using AVR microcontroller (both PRNG and TRNG). So I would like to get suggestions about different sources of entropy for TRNG and algorithms for PRNG. Also wanted to test the randomness. And What is chaos theory...
  38. B

    Luminance and illuminance of multiple point light sources

    Since there was some confusion previously where this post was mistaken for "homework" let me underline now *** THIS IS NOT HOMEWORK *** I've finished university 20 years ago, so this has nothing to do with any schoolwork or anything like that. I'm simply trying to understand some papers I'm...
  39. W

    Mesh Current Method with Dependent Sources

    Homework Statement Homework Equations V=I*R The Attempt at a Solution I started writing the equations for each loop. Loop 1 -> I1=8A Loop 2 -> -6Ix + 4I2 + 2(I2-I3) =0 and Ix=I4-I2 Loop 3 -> I don't know how to approach the dependent current source here. Loop 4...
  40. D

    Sinusoidal sources and complex power

    When calculating power in a given circuit, why is the complex conjugate of the current used to compute power?
  41. V

    Is g affected by other sources of gravity?

    Earth shouldn't alone make the value of g=9.81m/sec^2. There is the moon, all the planets and our sun (ignoring the outstanding multitude of outer space for my simplicity) and all of these bodies must have some influence on everything that's on Earth. So if we want to find the real acceleration...
  42. A

    Suggestions for sources with detailed calculations in quantum field theory.

    Can you suggest any source available on internet which may be particularly helpful for those studying/brushing up knowledge of classical or quantum field theory without help of any teacher or friend? Some calculations are at first not so straightforward and there are many types of calculations...
  43. Q

    Engineering LC circuit analysis problems with 2 voltage sources

    Homework Statement . In the following transient circuit, assume at t<0, the circuit is at steady state. Find v0(t) for t>0 http://sphotos-b.xx.fbcdn.net/hphotos-ash3/c0.0.354.354/p403x403/546839_509413575744829_42997155_n.jpg Homework Equations The Attempt at a Solution The...
  44. X

    Circuit with two voltage sources (Kirchoff Rules)

    Homework Statement The circuit shown in the figure below is connected for 3.10 min. (Assume R1 = 7.90 Ω, R2 = 2.60 Ω, and V = 16.0 V.) The circuit shown in the figure below is connected for 3.10 min. (Assume R1 = 7.90 Ω, R2 = 2.60 Ω, and V = 16.0 V.) Homework Equations Kirchoff's...
  45. F

    Multiple in-phase AC sources to a load

    I'm trying to figure out how multiple AC sources which are in phase would be able to be used sequentially to power a load. This all started as I read some literature about solar PV panel systems which had a wiring diagram to tie output from the inverters directly into the electrical panel split...
  46. T

    Adding parallel current sources?

    Homework Statement I am somewhat confused about when you can add parallel current sources: Are the sources in the diagram I drew - A - in parallel? To me they look like they are but I am not sure... Is there an easy way to visualize these problems?
  47. J

    What are the best online help sources for dynamics?

    I used to watch youtube videos for general physics and statics but I can't seem to find good help sources for dynamics. Does anybody know of a good youtube channel that has helpful videos for the dynamics course or any other websites that help make more sense of the class? If not, can...
  48. B

    Prove Electric Field Lines Go from High to Low Voltage Sources

    Homework Statement In my electromagnetism lab, we had one electrode connected from the negative end of a power supply to one end of a conductive sheet, and the other electrode connected from the positive end of the supply to the other end of the conductive sheet. The potential difference of...
  49. U

    Engineering Solving a Circuit with Current Sources and Resistors

    Homework Statement The problem is attached below.Homework Equations The Attempt at a Solution I tried reducing the circuit by applying a source transformation to each pair of current sources and resistors. I reduced the CS and R at the upper left to an 8V source and 4-ohm resistor in series...
  50. Y

    Two ideal dc sources and a resistor with lengths involved

    Ive been given an assignment with the question being question 13of the following pdf: http://vlsi-eda.cm.nctu.edu.tw/course/ICT_12Summer/hw/HWCh4.pdf (note this isn't my actual assignment i just found this one on the internet that happened to be the same question that i was looking for) Im...
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