What is Diode: Definition and 567 Discussions

A diode is a two-terminal electronic component that conducts current primarily in one direction (asymmetric conductance); it has low (ideally zero) resistance in one direction, and high (ideally infinite) resistance in the other. A diode vacuum tube or thermionic diode is a vacuum tube with two electrodes, a heated cathode and a plate, in which electrons can flow in only one direction, from cathode to plate. A semiconductor diode, the most commonly used type today, is a crystalline piece of semiconductor material with a p–n junction connected to two electrical terminals. Semiconductor diodes were the first semiconductor electronic devices. The discovery of asymmetric electrical conduction across the contact between a crystalline mineral and a metal was made by German physicist Ferdinand Braun in 1874. Today, most diodes are made of silicon, but other semiconducting materials such as gallium arsenide and germanium are also used.

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  1. Q

    Understanding Diode Display on a C.R.O.

    i have to draw the c.r.o. display for a diode, is it just the same as for an a.c. input but with the parts that were below the x-axis, intead reflected in the x-axis?
  2. S

    I-V characteristics of a silicon p-n junction diode

    Hello all, I've been tasked with drawing the I-V characteristics of a silicon p-n junction diode and I've managed to do that fine. Now, I've been tasked with showing how this curve will vary with temperature (200-400 deg.c) and by illumination with light of photon energy greater than the...
  3. Q

    Redrawing Circuits for Diode Analysis: Is It Valid?

    in the diagram below, the voltmeters are as near to perfect as possible, the cell has negligible internal resistance. the red blob is a conducting diode, and the green blob is non-conducting. the coloured boxes are resistors. in order to work out the current through the red diode, is it ok to...
  4. N

    Diode Configuration in Protection Circuit: Nose-to-Nose or Tail-to-Tail?

    Hi All, I'm replacing a switch in a piece of equipment. I'm looking at the circuit diagram and the actual circuit, and I notice that the diodes in the circuit aren't wired as they are in the diagram.:rofl: The HI signal is dc from 0-1 Volt and LO is ground. Is there going to be any significant...
  5. T

    What happens when you shortcircuit a pn diode?

    A thought experiment: (note that this comes from a student with only amateur experience in solid state physics) suppose you could shortcircuit a pn diode... ie you just link a wire between both ends, or maybe even bend the pn diode in a ring (so you'd have a n-surface between two p-surfaces...
  6. C

    A Commuter Diode Explanation Problem

    I have been trying to figure how a commuter diode effectively works in a circuit with a coil. I know that once the electric/magnetic field collapses in the coil after the current is cut to it that it induces a current in the opposite direction on the diode, which can only travel one way. But...
  7. S

    How can I determine the junction area of a diode?

    Hi Guys! How are u my friends? Well i want to ask u one important thing! Please tell me the way to find out the junction area of a diode Thanks in advance
  8. S

    How is the junction area of each diode calculated in this circuit?

    Hi Guys! My Question is this: Dsign the circuit of the fig: so that Vo= 3V when IL = 0 A AND Vo changes by 40mV per 1mA of load current. the value of R = 4.8Kilo ohms. find the juction area of each diode (assume all four diodes are identical) relative to a diode with 0.7 V drop at 1mA...
  9. S

    Transfer Characteristic of a diode

    Hi Guys: My question is this for the circuit in the 1st fig: sketch the transfer charcteristic "vo" versus "vI" the answer of this question is the 2nd fig. but i want to know that what is the logic behind this sketch or in other words how we can draw such a sketch. Thanks in advance
  10. Crumbles

    What is the relationship between a laser's gain curve and its natural linewidth?

    Can someone please explain what exactly the gain curve of a laser is? Is it exactly the same thing as the natural linewidth of the laser [a graph of intensity vs frequency] or am I off track? I found this graphhttp://www.phys.ksu.edu/perg/vqm/laserweb/Ch-5/C5s1p5.htm that tries to explain...
  11. 0

    Pn junction problem in diode

    when it comes to pn junction in diode, p and n are doping semiconductors. if P and N semiconductor are contacting each other, some holes in P and some electron in N are combined. that is, they are recombined. this recombination caused the current, very small. I was wondering that...
  12. C

    Modulating a diode laser with sound

    http://www.eweek.org/site/DiscoverE/PDFs/middle/First%20you%20see%20it%20Then%20You%20Hear%20It.pdf In my Photonics & Fibre Optics class today, our lecturer showed us a "Modern day photophone" he created for an easy $15 AUD (1AUD = 80US cents) I did not have time to ask him how to make one...
  13. E

    Physics - semiconductor diode.

    The problem is an experiment has to be set up to investigate how the breakdown voltage (which occurs by a large reverse potential difference is applied to the diode, and the diode then passes a large current) of a semiconductor diode is affected by temperature. My problem is how can I vary...
  14. S

    Understanding Diode Output Waveform Reversal

    Sketch the output voltage as a function of time. The AC voltage source is V_{o}cos(\omega)t with V_{o} = 10V and \omega = 2000rad/sec. I have posted a diode circuit question in the attachment Ok, I think it should be a sine curve with a 10 V amplitude but am not too sure about the period...
  15. S

    Organic light-emitting diode

    has anyone come across any website with good information on OLED technology. I'm not really looking for the technical details. What I?m interested in is a general overview of the technology. What it is advantage/disadvantages , applications, history. Stuff like that. i would really...
  16. U

    Physics Behind Generating a Small Current with a Diode

    If you put a diode in circuit with a piece of metal, heat the metal so the electrons start jiggling about the diode should let only the elctrons going in a certain direction through thus creating a small current. I read somewhere this does not work but it did not explain why, or does it work in...
  17. J

    How a Diode Works: Semiconductor Silicon Circuit

    How does a diode work? Or more precicely how does a semiconductor such as silicon only allow current to flow one way around a circuit?
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