Questions tagged [electronics]

Electronics is the study of electric circuits and electrical components, and the design of useful devices. Some questions in this tag may be more appropriate for the [Electrical Engineering(https://electronics.stackexchange.com/) SE site.

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What do the $E$ and $B$ fields look like around a length of pipe, excited from one end by a Class A amplifier?

Diagram here: I'm looking for help modeling the $\mathbf{E}$ and $\mathbf{B}$ fields around a length of pipe. One end of the pipe is connected to the collector of a transistor in a Class A amplifier....
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What's difference between Watt Electric ($\rm We$) and Watt ($\rm W)$?

So, I'm learning about Radioisotope Thermoelectric Generator (RTG), and wherever I read about it (in websites, in textbook [Fundamentals of Nuclear Science and Engineering]), the unit used for its ...
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Is it really true that radios work better in mountaneous region than in cities?

I was recently travelling somwhere with my family. During the journey we had to pass through a mountaneous terrain. My mother suddenly switched on the radio of car and it was so clear. Is this true ...
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Why does Si donate its own electron to Al in a p-type semi conductor losing its own stability?

Things I have known or been taught before asking this question: Every electron does not absorb same amount of energy from the environment. So there are some electrons in a semiconductor which can ...
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What exactly is being alluded to here with regards to the atomic lattice and electron flow? [duplicate]

I am currently studying the textbook Learning the Art of Electronics: A Hands-On Lab Course by Thomas C. Hayes, with the assistance of Paul Horowitz. Section 1N.2 Three laws says the following: Why ...
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Equation for total capacitance of the tline unit cell

Is there a simple equation to express the total Capacitance of this differential line? I am not sure how $C$ and $C_m$ are related to the final equation $C_{total}$.
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MOSFET in saturation mode [migrated]

A MOSFET in saturation mode behaves like a constant current source but a current source has infinite output resistance. But to make it work like an active load instead of passive load like resistor we ...
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1answer
57 views

Why do we use Boltzmann distribution rather than Fermi-Dirac distribution in a transistor?

Considering electrons are fermions I would think it is better to use Fermi-Dirac distribution when discussing the physics of the electrons and holes in a transistor. However, I have been told ...
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Can we make a microstrip analog of a 3D microwave E plane Tee

I need to make the 2d analog of a microwave E plane tee.The microwave Eplane tee has 3 ports and it divides a wave input at port 3 into two 180 degree out of phase waves at the 2 output ports. I want ...
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1answer
32 views

Is it possible to draw an EK diagram for the infinite square well?

EK diagram is usually talked about in the context of semiconductors, but can we draw an EK diagram for situations that don't involve semiconductors?
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Why cannot electrons constitute base current in an NPN transistor, but only when combined with holes of P side?

Several textbook's introduction to base current Ib in an NPN transistor is like "As the base is lightly doped with P type impurity, the number of holes in the base region is very small, and, ...
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1answer
33 views

How effective are privacy screens at blocking blue light in the presence of other protective measures?

For quite a while, I've been using privacy screens, which not only increase... well, privacy, but also purportedly block blue light. However, web search results generally yield very broad statements ...
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Best way to calculate $T_0$ of a laser diode material

In the following website it is described that to calculate the T0 of a laser diode, I have to take a laser of specified geometry, find the threshold currents at different temperatures and plot their ...
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1answer
37 views

How do devices control how much power they use?

In power systems (Australian for reference) the grids run at a constant voltage of 220V. I’ve heard of switches were less voltage being used is created by adding more resistors for example to dim ...
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28 views

Does effective internal resistance of batteries depend on their size? If so how?

It was asked to us by our professor- Consider the AA and AAA batteries, what do we think will happen to the internal resistance, will it increase or decrease or can we actually tell something about it?...
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How can a water-resistant device can not have a dust resistance to it? [closed]

I have read about IP Ratings on how it rates on the resistance of the device to either dust or water. But I've seen some devices that have an IPX7/IPX8 resistance (one example would be the Fold 3). ...
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1answer
38 views

Voltage across battery which is being charged

When I connect my 7 V battery (having 7 V voltage ) to a 10 V power supply then across the battery it shows the voltage being the same as the instantaneous voltage of the battery. Now if I connect the ...
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How is data transferred between devices?

If you send a text from your phone to your friend, do electrons move from your phone to your friend's phone? How is text transferred (physics wise)? I am a programmer and I want to know how it is ...
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1answer
30 views

What is the wavefront quality of VCSELs? How does the wavefront quality of VCSELs compare to Fabry-Perot laser diodes and DPSS lasers?

I am currently looking at this VCSEL. According to the datasheet, it has a narrow spectral linewidth and emits a Gaussian beam, which are both properties that I find interesting. But I'm also ...
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How to experimentally verify, if the intensity of light from an External Cavity Diode Laser (ECDL) is shot noise limited?

I have an ECDL and i want to experimentally verify if it is shot noise limited or not. Any reference will be helpful.
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1answer
27 views

What photodetector parameters should I be focusing on, and in what priority, to maximise the performance of such an interferometer?

I'm trying to select a photodetector for an interferometry experiment. The interferometer will be trying to measure subtle vibrations occurring at a relatively high frequency (high kHz to low MHz). It ...
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1answer
37 views

Cathode Ray Oscilloscope [closed]

Is Cathode Ray Oscilloscope (CRO) a device that measures and displays using the electron beam from cathode rays? Are cathode rays its working principle? Does it mean that the line or point showed on ...
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1answer
44 views

Is sublimation of the metal filament in a vacuum tube the main reason for eventual failure?

I saw a question asking if metals sublimate, with some fascinating answers, which made me wonder if sublimation was the main cause of the eventual, and inevitable failure of vacuum tubes. High school ...
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What will happen if we place a charging inductor inside a constant electric field/ varying electric field?

For the sake of curiosity, i imagined a circuit in which a inductor is present in a constant/varying electric field , in that case there will be interaction of electric field and magnetic field , but ...
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1answer
80 views

Current contribution in a p–n diode under equilibrium

We say that under equilibrium, no further movement of majority carriers takes place due to the immobile ions or the electric field or built in potential stops it. But in many cases and videos I seen, ...
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1answer
23 views

Shifting of Energy levels in PN junction under Equilibrium

My question is during equilibrium is achieved under no biasing, why it is that in fermi level diagram representation fermi levels are raised in p type nd lowered in n type. Is it not possible we ...
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1answer
38 views

Diffusion and Drift Current under no biasing of a PN junction Diode

In a PN diode, I get the point that total current is zero due to drift and diffusion current contribution cancels their effect when depletion region is formed. My question is even though just for a ...
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2answers
71 views

What does this symbol represent in circuits?

I was watching a YouTube video on the superposition theorem and came across a symbol : The symbol on the right . He says it's a current source , Is that all it is ? Is there a name to this so that I ...
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Why are polycrystalline solar cells shinier than monocrystalline solar cells?

Being shiny reduces the efficiency of the solar cells. Additional to the grain boundaries that polycrystalline solar cells have that gives resistance to the current flowing in them, they are shinier ...
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2answers
141 views

Why do we use high resistance wire in potentiometer?

I was recently learning about potentiometer and , my teacher told thta potentiometer wire has very high resistance , but if potentiometer wire has very high resistance , wont the current skip ...
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1answer
25 views

Is the dynamic resistance of a diode due to the narrowing and widening of the depletion zone?

All diodes have a built-in voltage. When a diode is connected under forward or reverse bias, the depletion region either widens or narrows. Obviously, the barrier height also increases or decreases ...
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2answers
63 views

Is there a small spark every time a switch is closed to engage a circuit?

Suppose we have a simple circuit with a resistor $R$ connected to a DC voltage source $V_{\text{batt}}$. The circuit can be enabled or disabled by a switch. The dielectric breakdown of air is $E_{\...
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3answers
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Laser diode tests - voltage sweep vs current sweep. What's the difference?

I can't wrap my head around it. There's no current without voltage (except eddy currents), and there's no voltage if there's no current, when you pass the current through a diode. So why do people ...
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1answer
86 views

Dynamic resistance of diodes and the depletion zone

According to Resnick, Walker & Halliday's Fundamentals of Physics (10th edition), Figure 41-15 shows why a p-n junction operates as a junction rectifier. In Fig. 41-15a, a battery is connected ...
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3answers
206 views

How does a transistor work?

Here we can see a Bipolar Junction Transistor (BJT), which has a common base configuration. My instructor recently explained to me its working principle, but I didn't understand his explanation ...
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26 views

Unbiased PN junction Diode

I have certain doubts regarding the formation and movement of majority charge carriers when a p type and n type semiconductors are fused together. When electrons and holes mover from p to n and n to ...
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2answers
27 views

In LED's do the number of charge carriers (electrons and holes) decrease with time?

According to page-1268-69 of Halliday, Walker & Resnick's Fundamentals of Physics (10th edition), To emit enough light to be useful as an LED, the material must have a suitably large number of ...
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1answer
48 views

In semiconductors, do free electrons and holes ever mix to become neutral?

According to page-1262 of Fundamentals of Physics by Halliday, Resnick & Walker (10th edition), Both the electrons in the conduction band and the holes in the valence band serve as charge ...
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23 views

Static charge behavior (in ref to Grob's Basic Electronics book, 13th Ed, p33)

I have a question pertaining to the aforementioned book in a section titled "Potential between Different Charges". The paragraph goes as follows: When one charge is different from the ...
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57 views

Why do I hear static when I plug in my earphones incorrectly?

I use simple earphones which are wired with my laptop. Most of the times I unconsciously plug them in without looking and at times instead of going in the port they touch the laptop body near the port ...
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1answer
20 views

Will the depletion layer of a p-n junction stay extended after being disconnected from the circuit where it was connected under reverse bias?

We know that the depletion layer/region becomes longer when a diode is connected under reverse bias in a circuit (Is my grammar correct?). Now, my question is, if we then disconnect the diode from the ...
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24 views

Is there a difference between $\rm SiO_2/Si$ and $\rm Si/SiO_2$ when describing the substrate of a field-effect transistors?

I've seen in different papers that the substrate of a FET is SiO2/Si or Si/SiO2 are they describing the same thing or is the order important?
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1answer
31 views

Why does the reading of load cell changes with change in the mounting styles?

I'm working on a project in which I have connected the loadcell to Arduino via the HX711 ADC. I mounted the load cell in two different configurations as shown in the image. With the connections, ...
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2answers
31 views

Center tap transformer and full wave rectification [closed]

I am trying to understand center tap and full wave rectification and struggling with flow of current. My understanding of center tap is that, voltages will be 180 out of phase for the 2 parts in ...
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16 views

Why can we connect multiple battries together to get higher voltage or current but not conect multiple DC adapters for the same purpose?

There are reasons as to why connecting 2 DC sources is a bad idea, but multiple batteries are connected to get higher voltages, like batteries used in inverters, or making Lithium ion battery packs.
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2answers
31 views

Estimating parameters for diode model from experimental data

I have got a set with experimental data of the voltage drop on a diode an its corresponding current. The general model of a diode is $$ I = I_s \left( e^{V/nV_T} - 1 \right)\ , $$ and I want to ...
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25 views

Capacitance ratio in potential energy

In reading about quantum dots in nanowires, the potential energy of an electron due to a gate voltage $V_g$ was given as $-eV_g(C_g/C)$ where $C_g$ is the capacitance of the dot with the gate and $C$ ...
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23 views

How to find the voltage threshold at which diode switches states? [closed]

The diode in the figure is described by its offset model: $U_{D0} = 0.6 V$ and $r_d = 0$. Knowing that $E_0 = 3.9 V$, find the voltage threshold $u_l$, at which the diode switches to its opposite ...
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1answer
28 views

What is the formula for ripple voltage in integrating circuit?

With a rectangular wave input Vin and a typical RC circuit with output taken across the capacitor, what is the formula to calculate Delta V due to ripple?
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35 views

How can you expect a "fractional resistance change" with change in temperature?

I was learning about temperature dependence of resistance on a website that states as follows. An intuitive approach to temperature dependence leads one to expect a fractional change in resistance ...

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