What is Junction: Definition and 223 Discussions

A junction, in the context of rail transport, is a place at which two or more rail routes converge or diverge. This implies a physical connection between the tracks of the two routes (assuming they are of the same gauge), provided by points (US: switches) and signalling. Junctions are important for rail systems, their installation into a rail system can expand route capacity, and have a powerful impact upon on-time performance.

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  1. Onyx

    I Israel Junction Conditions: Finding Continuous Metric Across Shell

    A Relativist's Toolkit (2004) lists the Israel junction conditions as: ##1. [h_{ab}]## ##2. S_{ab}=[K_{ab}]-[K]h_{ab}## Where ##S_{ab}## is the stress-energy tensor of the shell only, and ##[K_{ab}]## and ##[K]## are ##K_{ab}^--K_{ab}^+## and ##K^--K^+## respectively. My understanding is that...
  2. Mayan Fung

    I Measuring the built-in potential of a pn junction

    I am thinking about the reason why we cannot probe the built-in potential across a diode with a voltmeter. Obviously, a diode is not an energy source, so it is impossible for it to show a voltage reading. After doing some research, I found some explanations and some questions about them. 1. The...
  3. Mr_Allod

    Total Josephson current through junction with magnetic field

    Hello there, I am given a diagram of a Josephson Junction like so: With a magnetic field ##B = \mu_oH## in the z-direction. I'm reasonably sure ##d_x,d_y,d_z## are normal lengths, not infinitesimal lengths although that is up for debate. Using the above equations I rearrange the expression...
  4. Mr_Allod

    Built in Voltage of 3-Layer PN Junction

    For a normal PN junction I would try to find $V_{bi}$ by integrating the carrier density (eg. the electrons n) from one region to the other: $$\int_{n_{p0}}^{n} \frac {dn}{n} = \frac {q}{kT}\int_{V_p}^{V_n} dV$$ Which would yield: $$V_{bi}=V_n-V_p=\frac...
  5. U

    What Explains the Lack of Current in a PN Junction at Equilibrium?

    Consider a PN junction doped with say phosphorous on the N side, and Boron on the P side. Initially, there is an opportunity for the electrons just below the N conduction band to drop to the lower available energy states just above the P valence band. This leaves the N side positively charged...
  6. rkgjet

    Space charge region of p-n junction diode

    does np=ni^2 holds even the space charge region of a pn junction diode?
  7. S

    Electrical USA Building Codes: Inside Junction Boxes with Terminals?

    (USA) building codes require that wires that are spliced together must be contained in electrical boxes that are accessible - e.g. you can't splice together wires in an attic. So one often finds electrical boxes for ceiling fans or electrical outlets also serving as junction boxes in the sense...
  8. P

    Engineering Current variable given through junction crossing

    I'm supposed to solve this using nodal analysis. No biggie! I'm just not sure how to handle ia. I've never seen a current indicated in a junction crossing. I searched the web and my textbook and found zilch. I asked a GSI and was informed it is indeed written where is supposed to be. Within the...
  9. M

    What Type of Chemical Bonds Exist Between Tight Junctions in Human Cells?

    I know tight junctions between adjacent cells are very strong and the gaps are practically zero. But what types of chemical bonds are they? Are they covalent bonds or hydrogen or ionic bonds? I mean between the claudin and occludin proteins.
  10. T

    Fundamentals of the PN Junction

    Unbiased circuit (no driving voltage source) ************** Fig 1 The N-type material has a tendency to donate electrons to the P-type (i.e. absorb holes from) across the PN junction via diffusion current exclusively within the conduction band of both materials. It does so after those...
  11. somasimple

    What is a Liquid/Liquid Junction Potential and Its Role in Batteries?

    Hi, Is there a liquid/liquid junction potential between two liquids of same composition but different concentrations WHEN there is no external electrical circuit and then NO electrodes? (Of course this potential is not measurable). Thanks,
  12. A

    Effect of doping concentration on the depletion width of p-n junction diodes

    My question for now is as follows: Why does a high doping concentration causes a decrease in the thickness of depletion region. Any help will be highly appreciated! Thanks a bunch Regards!
  13. E

    Bohr-Sommerfeld, WKB, and current-biased Josephson junction

    I've already found the turning points, in the case of the left turning point, the local minimum of the potential, ##\delta_{min}=1.11977## when evaluating for an arbitrary value of current ##J=0.9I_C##. The left turning point is therefore ##\delta_r=2.48243##. I know the Bohr-Sommerfeld...
  14. Praveen1901

    B What is the purpose of the depletion region in P-N junction semiconductors?

    I'm new to semiconductors. While I was studying types of biasing in semiconductors, here's what I read - 'In forward biasing, the width of the depletion region is reduced.' Here's what I thought - Since the potential barrier is reduced in the junction due to external potential, the diffusion...
  15. tworitdash

    A Waveguide Junction TM/TE combination

    In the paper here, it says no matter what the waveguide structure is, if the smaller waveguide has a TM mode and the larger has a TE mode, then the coupling (Inner cross product \int\int_{S_{smaller-waveguide}} (E^{small}_{transverse} \times H^{large}_{transverse}) . \hat z dS, where z is the...
  16. Terrycho

    (Bipolar Junction Transistor) The Current Gain of Common Base Amplifier

    Everything is okay besides the current gain of this circuit, which is "g" there The formula of current gain is I_out/I_in If I call the current flows to R_e I_2, according to KCL, the following formula must be satisfied. I_in + (β+1)I_b = I_2 Therefore, to know I_in, we should use the...
  17. I

    Programs Topics at the junction of AdS/CFT and quantum information

    I have been asked to draft a (informal) research proposal for a PhD thesis. I have some background in quantum information and my interests are leaning towards the AdS/CFT correspondence. I was wondering if you could suggest a few (preferably recent) theory papers at the junction of quantum...
  18. Peter Alexander

    Engineering Compute the voltage gain of this bipolar junction transistor circuit

    This is the given schematic. The result should be $$A_u = \frac{R_b g_{21}}{1 + R_b g_{22}} = -50$$ and the way I wanted to tackle this problem is by stating $$A_u = \frac{-R_b i_2}{u_1} = \frac{-R_b (g_{21} u_1 + g_{22} u_2)}{u_1} = \frac{-R_b (g_{21} u_1 + g_{22} u_2)}{g_{11} u_1 + g_{12} u_2}...
  19. S

    Wrong statement about a p-n junction

    Homework Statement A p type semiconductor is brought into contact with an n type semiconductor to form p - n junction. Which statement is false? A. During forward bias condition, if applied p.d. overcomes the junction potential, electron will cross steadily from n - type side to p - type side...
  20. Aishikdesto

    Nature of charge at the junction of a composite wire

    Homework Statement Please help me answer thew question in the image.[/B] Homework Equations Current Density J=conductivity X Electric field[/B] The Attempt at a Solution As the current density depends on the conductivity of the material through which the electrons constitutuing it are...

    Non uniformly distributed p-n junction related problem

    Hello guys, I stumbled upon this problem while studying non uniformly distributed pn junctions and finding difficulty solving this. Any help will be greatly appreciated. A diffused silicon p-n junction has a linearly graded junction on the p side with a = 2 x10^19 cm-4, and a uniform doping of...
  22. avner yakov

    What the difference between pin and pn diodes i-v curve?

    For my understanding there should be no big difference in i-v curve between regular p-n junction and p-i-n junction, the only difference i can think about is do to the bigger resistance of the intrinsic layer. The curve should look the same only the current will rise little bit slower, because...
  23. T

    Pn junction under forward bias

    If two batteries are connected such that positive terminal of one is in contact with negative terminal of other then we add the potentials so the potential will then be their sum. Similarly if a battery is connected to a pn junction diode such that positive terminal is connected to negative...
  24. S

    I Boltzmann Distribution: Feynman's treatment of p-n junction

    In Vol III, 14-4 and 14-5 of the Feynman Lectures (http://www.feynmanlectures.caltech.edu/III_14.html), Feynman gives a discussion of the p-n junction, in which he derives the diode characteristic equation via a nice, simple and convincing application of the Boltzmann distribution to the...
  25. Wrichik Basu

    Do carriers move across a p-n junction at 0 K?

    Often a band diagram is used to explain what happens when two pieces of the same semiconductor, one p-doped, one n-doped, are put together. I am a little confused about it, so here is my question. Initially and at ##0\mathrm{K}##, the surplus carriers should be confined to their respective...
  26. Z

    What Happens to Amplifier Gain When Connecting a Load?

    Hi Guys can you tell me, what will happen to the gain of the amplifier when a load is connected to the output terminals ?
  27. E

    The flow of electrons in a photovoltaic p-n junction

    Hi,how is the movement of the electrons in photovoltaic? I understand that there is n and p layer. What I do not understand is why the electrons does not move more directly to the p-side from the n-side. In the currect explanation it requires a circuitry. Thanx.
  28. E

    I Concentration of R-G centers in a PN junction

    Hey guys, Currently taking a semiconductor device fundamentals course and we are learning about R-G currents in the depletion region of a PN junction. Usually we just consider R-G centers as impurities to be avoided in the operation of a standard rectifying diode. However, I was curious as to...
  29. L

    Charge density in an abrupt p-n junction

    Homework Statement In an abrupt p-n junction we consider the junction between one side p-doped with ##N_A## acceptor atoms and another side n-doped with ##N_D## donor atoms. Initially the chemical potential is different in the two sides, but thermal equilibrium requires that the chemical...
  30. P

    Heat Transfer: Finding temperature at the junction

    Homework Statement A furnace is constructed with 0.5 m of fire brick, 0.15 m of insulating brick and 0.25 m of ordinary building brick. The inside surface-temperature is 1530K and the outside surface temperature is 525K. The thermal conductivities of the fire, insulating and building bricks are...
  31. C

    Why Does the Depletion Layer Affect Acceptor Atom Concentration in PN Junctions?

    Homework Statement I'm doing a course in solid state electronics and we just started PN junctions etc. I'm a bit confused. So here is what I know so far: Initially the P and N regions are separated by a a PN junction. At 300K as the acceptor atoms on the P side and donor atoms on the N side...
  32. D

    I Exploring PN Junction Loop: Fermi Level and Work Function

    Hi. So we have all seen the band diagram of a PN junction. In order for the fermi level to be the same on both sides, the P bands are shifted up or the N bands are shifted down. Now that the fermi levels are equal, what would happen if you bent the diode into a ring (annulus) shape? How would...
  33. Pao44445

    Finding Voltage Using Junction & Loop Rules

    Homework Statement find the voltage between a and d and terminal of each batteries Homework Equations Junction Rule and Loop Rule The Attempt at a Solution I got three equation JR : I3 = I1+I2 LR : 45-I3-47I3-34I1 = 0 45-I3-47I3+85-I2-18I2 = 0 I can't solve these...
  34. Deebu R

    Temperature at the junction of 2 wires

    Homework Statement The thermal conductivity of copper is 4 times that of brass.Two rods of copper and brass having same length and cross section are joined end to end. The free end of copper is at 0 degree C and the free end of brass is at 100 degree C. The temperature at the junction is...
  35. Dr. Manoj

    PN Junction Diode: Diffusion vs. Drift Current

    What exactly is difference between diffusion current and drift current?
  36. Dr. Manoj

    Zener Diode Breakdown: Effects on PN Junction & Holes/Electrons

    Once the zener Diode is formed by breakdown of pn junction Diode, potential across Diode remains constant. If we again change the configurations from reverse bias to forward bias, is it possible to get back the normal pn junction as before the breakdown and will potential across junction be...
  37. mertcan

    What is the derivation of built in voltage for a P-n junction?

    hi, I am looking a derivation of built in voltage, but the only thing I could find is a statement: built in voltage can be derived from band diagram with the Fermi energy constant throughout the device, or from equating the drift current through the junction equal to the diffusion current. I...
  38. D

    I PN Junction Current: Understanding Dependence on Parameters

    Hi. I'm trying to understand how the current in a PN junction depends on various parameters. I have found this formula in Ashcroft and Mermin. It looks like the current will increase if we decrease the density of donors and/or acceptors, Na and Nd. Is this correct?
  39. E

    I Double heterostructure junction in forward and zero bias

    Hi! When dealing with a pn homojunction, it is easy to see the features it has at equilibrium, and also the features it has with forward/reverse bias. Plots show the constant Fermi level at equilibrium and the different Fermi levels for a forward bias; moreover, examples show how much the bands...
  40. F

    Junction affects the flow of water?

    Homework Statement based on this picture in the notes , the author gave that if D is below B , then h2 and Q2 = 0 , what dos it mean ? what does it mean ? water cannot flow out and in from B ? please ignore the pencil sketched-part Homework EquationsThe Attempt at a Solution
  41. E

    I Built-in potential in pn junction

    Hello! The (potential) energy of an electron in a solid structure is always negative; also the E_c and E_v levels (conduction band and valence band limits) are negative, in the band diagram of a pn junction. When the junction is built and thermal equilibrium is reached, the depletion region...
  42. R

    Finding currents using the junction and loop rules

    Homework Statement Homework Equations i1+i2-i3=0 50i1+75i3=1 100i2-75i3=1 The Attempt at a Solution matrix A=1 1 -1 0 100 -75[/B] 50 0 75 matrix B= 0 1 1 i1= -6ma i2= 23ma i3= 17ma My instructor gets i1= 6ma...
  43. F

    Josephson Junction: Perpetual Motion System?

    Isn't the Josephson junction in effect a perpetual motion system ?
  44. E

    I Pn junction to reach thermal equilibrium

    Hello! Some of the processes caused by a pn junction are not clear for me. Just after the contact between the p and the n region, a migration of charges happens in a semiconductor junction in order to reach an equilibrium condition. A valence band and a conduction band are present in both...
  45. K

    Thermodynamics Tee Junction Problem

    Homework Statement T junction 5 kg/s of methane enters on one side at P1 = 1 MPa, T1 = 400 K, and 1kg/s of methane enters on the otheras a saturated liquid at P2 = 1 MPa. The two streams are mixed and emerge at P3 = 1 MPa. Determine the temperature of the discharge stream (T3).Homework...
  46. F

    A Israel junction conditions for simple metrics

    Hello, I am curious as to how one appropriately matches an interior and exterior solution in GR, i.e. where the interior corresponds to the field of some finite spherical mass (perfect fluid sphere, for the Schwarzschild interior solution). Specifically, looking at both the Schwarzschild...
  47. G

    Depletion zone and current in forward-biased PN junction

    Hello. I've learned that in PN junction, forward-biasing on it pushes holes in P-type and electrons in N-type toward the junction so depletion width is reduced. Is it due to that in N-type side(P-type side), pushed electrons (holes) are recombined with holes (electrons) in depletion zone? And...
  48. G

    Depletion zone and current in forward-biased PN junction

    Hello. I've learned that in PN junction, forward-biasing pushes holes in P-type and electrons in N-type forward junctions so depletion width is reduced. Is it due to that in N-type (P-type), pushed electrons (holes) are recombined with holes (electrons) in depletion zone? And what is true...
  49. vetgirl1990

    Why is the Junction Rule not applying in my circuit?

    Homework Statement In my lab today, I created a circuit with resistor (R1) in series with a set of resistors in parallel (R2//R3). Using an ammeter, I measured: I1 = 2.30mA I2 = 1.25mA I3 = 0.38mA Homework Equations Junction Rule: ΣI = 0 The Attempt at a Solution So applying the Junction...
  50. A

    Short circuited illuminated PN junction

    I understand why the potential difference across the pn junction decrease in case of the open circuit, but why does it decrease in the short circuit, And why in the J-V equation we use V = Voc ( where qVoc is the energy between the quasi fermi levels) and what if the quasi fermi levels aren't...