# Tag Info

33

The electrons themselves don't move all that fast. The wave energy is the part that moves quickly. Picture it this way. You have 500 meters of pipe, with a small hole at the other end. The pipe is full of water and you increase the pressure at your end. Water will flow out the other end immediately. This is the electrical energy (pressure) and the ...

14

In fact, electron's speed is not so fast that light bulb glows up immediately. It is the electromagnetic field which travels in the circuit at near the speed of light that is resposible for it. After turn on the light, electron only acquires a little speed in addition its thermal speed. The thermal speed of electron can be estimated by \$mv^2/2\approx ...

4

Depending on your view, there is electronics with other charge carriers. It is commonplace to have semiconductor devices where the relevant carriers are holes! Furthermore, batteries and electrolysis relies heavily on ions as charge carriers (but hardly count as electronics). I guess genuine electronics with ions will be difficult as charge carrier mobility ...

4

An electrical spark will vapourise part of the surface where it is generated. With a large spark this can cause visible pitting, though if the spark is small you may only be able to see the damage under a microscope. Anyhow, just as in a flame metal ions present in the vapour can be excited by collisions and then decay to emit light. The colour of the light ...

3

According to the Review of Particle Physics (Section 33.7.4 of the 2014 edition) there are two main causes of radiation damage for electronic devices: Bulk damage due to displacement of atoms from their lattice sites. This leads to increased leakage current, carrier trapping, and build-up of space charge that changes the required operating voltage. ...

3

Ionizing radiation loses energy in matter by creating electron-ion pairs. Suppose you have an 1 MeV charged particle stopping in a silicon crystal. The first ionization energy for free silicon atoms is about 8 eV. The ionization energy will be a little different for silicon atoms on the lattice, but not grossly so: your 1 MeV charged particle is going to ...

3

If your phonograph cartridge uses a piezo-electric pickup, the cartridge may have acted as a rudimentary crystal radio receiver. In a piezo-electric pickup, the stylus contacts a crystal and creates an electric current while jiggling as it moves through the grooves of a record. It's likely that while you were jiggling the apparatus, you found the exact ...

3

It just shows that the item is a meter. The arrow represents the indicator on analog meters.

2

From your question is sounds as if you understand how parallel LC circuits work, in which case it's easy to explain how an LC circuit works as a tuner. Any particular parallel LC circuit has a natural resonant frequency. If we assume the LC circuit is perfectly lossless, then if we apply a driving voltage at the resonant frequency the energy stored in the ...

2

I believe that the reason may be at least two-fold: (1) For dopants to be effective, the energy level introduced by the dopant has to be a shallow energy level, not a deep energy level. A shallow level means that the impurity level is very close to the valence or conduction band, so it is easy to thermally ionize the dopant atom and have its electron (or ...

2

Even in a 'DC' circuit, diodes can be useful for, e.g., current steering. Consider a rudimentary battery backup system: When the primary 14V supply is present, the LED is on while D2 and R2 prevent the battery from charging at too high a current. When the primary 14V supply isn't present, D1 'disconnects' the LED and regulator IC from the battery while ...

2

It is not that the interviewee experiences a longer delay - but that you see the whole scene delayed by the same amount. Delays are caused by a number of factors: sound is conveyed in packets that are digitized, compressed, and converted at various points along their path: at each point they experience at least "one packet's worth" of delays (can't send ...

2

I think it might be one of those things where people do something because everybody does. I agree with you, a figure of merit that includes noise would make more sense. But, as the circuit designer that I am, I could also say that that wouldn't be the end of it. For example, in the classic trans-impedance amplifier used for these kind of detectors the ...

2

The answer is not simple. The sensor you linked has 4 independent photodiodes, each with its own optical filter, and each gives a different result. In a perfect world, the 3 color sensors would exactly cover the overall spectrum of the white sensor, with no gaps or overlaps. AND the responsivity of each color sensor would be exactly the same as the white ...

2

Can we have electronics with charge carriers OTHER than electrons? Yes, see what Sebastian said above. And see the physicsworld article Taming light at the nanoscale: "Look around, and you will probably see numerous electronic and optical gadgets, such as mobile phones, personal digital assistants, laptops, TVs and digital cameras. These may all do ...

2

As a Physics student I've found really useful Jacob Millman's Microelectronics, which offers a thorough insight into the world of Electronics, both digital and analogue. It covers a wide range of topics, from semiconductors to transistors (BJT, FET - both MOSFET and JFET) to operational amplifiers, with chapters devoted to the explanation of the concept of ...

2

The current in other Optoelectric devices like LED and photocells are flowing from a source of voltage to the devices but in case of solar cell, current flows from the cell to the load and thus current in circuit is taken to be in opposite ( or negative direction ). The voltage is still positive. Therefore, the fourth quadrant. Someone else may provide you ...

2

Yes, oscilloscopes will eventually wear out. They last a long time, if they are taken care of. There are many vintage scopes out there that are 30+ years old that still work perfectly. Here are a few examples of failure modes. There are probably more. 1.) Phosphor coating on the inside of the tube wears out, causing the display to dim. 2.) The tube develops ...

2

A capacitor can contain a certain amount of charge for a given voltage: $$Q = CV$$ When you have more than one capacitor in parallel, they have the same voltage (because they are in parallel), and each stores a certain charge. The total charge (at a given voltage) will be the sum of the charges on all the capacitors. Now if you have a certain load (for ...

1

No! Any slab, however flat, will have roughness much larger than the inter-atomic crystal spacing and hence continuous contact at the atomic level will not be possible. The junction will behave as a discontinuity for the flowing charge carriers. On adding precisely a small quantity of pentavelent impurity, in a thin p-type semiconductor wafer, part of the ...

1

Although there are different types of "radiation," their common effect is to transfer some/most of their energy to the material they "hit," resulting in the breaking of the atomic bonds and or structures of the material. When "enough" bonds and/or structures are broken, the material will fail. Since the electrical characteristics of electronic components are ...

1

A Zener is not like a normal diode. A normal diode lets current flow in only one direction and needs to be installed in the correct direction. A Zener diode is placed in the opposite direction, against the flow of current. A Zener diode will prevent current from flowing until it reaches a certain voltage, depending on the diode rating. Once this critical ...

1

There is a very nice demonstration that you can treat holes as positively charged carriers in the Hall effect. As you may know, to observe the Hall effect we place a semiconductor in a magnetic field and pass a current through it. We observe a polarization (voltage) at right angles to both the current and the magnetic field as a consequence of the Lorentz ...

1

In a homojunction the barrier potential depends on the difference in Fermi levels been the n and p sides. If different materials are used (heterojunction) then there is an additional potential from intrinsic difference in electron affinity.

1

Consider a circuit with a capacitor, a voltage source, and a switch. Suppose the voltage source is DC and we flip the switch. If the capacitor is initially uncharged, then at the instant you close the switch current will flow as if the capacitor was not there. Instead of an electron crossing the capacitor, an electron will arrive at the negative capacitor ...

1

EMF is the total voltage that can be supplied by a source of electrical energy (e.g. battery/dynamo). Basically, it encompasses both the voltage that will reflect in the circuit and the voltage that is constantly used up to overcome the resistance r of the component itself. Voltage is equivalent to work done per charge (V= W/q), this applies to EMF as work ...

1

Yes. Whether the result is a good conductor depends on how localized electrons and holes in the respective bands are (or, saying the opposite phenomenologically: on their mobility). Their recombination time limits for how long you will have even just two charge carriers available for conduction. This tends to make such conduction very energy-inefficient ...

1

It is more often the case that the broadcast is delayed a few seconds so that if the phone-in participant says something that the show's producers don't like it can be easily censored.

1

It comes from the fact that most strobes are, or were, used to examine car engines. Specifically the distributor. Hence RPM

1

The stroboscopes we had at school, in a largely pre-electronic age, were simply rotating discs with a hole near the edge. You shone a light at the edge, and the RPM of the disc determined how rapidly the strobe would flash (as the hole passed in front of the light).

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