Questions tagged [electrical-engineering]

The tag has no usage guidance.

Filter by
Sorted by
Tagged with
1
vote
3answers
54 views

Does load on electromagnet affect its current?

If we make an electromagnet by winding 3000 turns on 5-inch-long cast iron bar, and provide $12 \;\text{V}$ and $2 \;\text{A}$ of current, it will produce the magnetic field with certain magnitude. ...
1
vote
3answers
40 views

Electricity supply in homes is AC but what about rms value that has only one direction? [closed]

In our homes, electricity supply is AC.but we have rms value in our homes...How do they relate? Is rms value generated in transformer or what??
1
vote
1answer
30 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 ...
3
votes
1answer
51 views

How does the Fermi level of different materials reach equilibrium when in contact?

I'm a college student studying semiconductors. I can't understand what is happening inside the materials when two or more different materials are in contact. Can I get some help? So, basically at ...
0
votes
1answer
42 views

What exactly carries power in a transformer?

Suppose we have applied a voltage to a transformer with an open secondary, we will get a certain flux in the core and a certain voltage at the secondary depending upon the turns ratio. Now, suppose we ...
2
votes
1answer
33 views

What is the explanation behind radio shadowing by people?

I called it shadowing but masking may be more appropriate, feel free to suggest a better question title after you read the following. I have an old clock alarm radio receiver that plays at the center ...
12
votes
14answers
4k views

How do electrical devices limit the current flow from a socket?

How does a home appliance limit the amount of current that flows through it? Are there some resistors set up in series in order to cut down the current flow before it actually reaches the device? ...
0
votes
2answers
70 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 ...
0
votes
2answers
481 views

Potential difference across a resistor in a simple circuit

In a physics worksheet that I have, I stumbled upon a simple circuit with a battery (with it's own internal resistance), a voltmeter parallel to the battery, and a variable resistor parallel to the ...
0
votes
2answers
167 views

Physics vs Electronics (Smartphone charger)

Basically, an electric charger consists of a transformer, which transfers electrical energy from one inductance to another.. َAs i imagine the process physically the first circuit (inductance) should ...
0
votes
2answers
74 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 ...
0
votes
0answers
12 views

Is it possible for the voltage drop across the depletion region in a diode to be more than the actual biasing voltage?

We know that there will always be a net current in the circuit between the two terminals of the forward biasing voltage source, however small the forward biasing voltage is (see @jonk 's comment). ...
0
votes
1answer
19 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 ...
0
votes
2answers
60 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_{\...
0
votes
1answer
670 views

How to calculate total power generated?

I have a circuit with a piezoelectric transducer which converts mechanical energy to electrical. The ceramic is connected to a 1 Megaohm resistor and a voltmeter which reads voltage. If I want to ...
0
votes
2answers
1k views

Explanation for transistor as amplifier

In transistor as an amplifier, we have NPN transistor (base in the middle and emitter and collector at the sides). The collector has electrons in majority because it is N-type. similarly, holes are in ...
0
votes
1answer
194 views

Mechanism of working of full wave rectifier using center tapped transformer

I am self learning semiconductors for past few days and i couldnot get the answer to the following question. How does a centre tap transformer rectifier function? I could not quite get to understand ...
5
votes
3answers
124 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 ...
0
votes
2answers
170 views

Grounding secondaries in isolation transformer

In an isolation transformer (I assume a 220v-110v step down transformer is also called an isolation transformer), you can ground either of the secondary leads. I'd like to know the following: If you ...
3
votes
0answers
54 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 ...
1
vote
1answer
46 views

Can the electric field of an EM wave have a component in the direction of the wave?

I am currently taking a course in electromagnetics and i've stumbled into a problem. On the Engineering electromagnetics book by sadiku there is a question with the electric field of plane wave as ...
0
votes
0answers
23 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?
-2
votes
2answers
30 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 ...
0
votes
1answer
46 views

Why are PWR's being build instead of FBR's or LMFBR's?

Why are PWR's still being built in modern times when we have the option to use designs that allow intake of raw uranium without the need for enrichment and allow for recycling of waste material. I don'...
0
votes
0answers
57 views

Ramsauer–Townsend effect and Thermal Runaway in Thyratrons / (vacuum tubes)

A few years ago an EE told me that the Townsend effect was involved in thermal runaway within vacuum tubes. I can't seem to find any specifics on this on the internet. Can anyone disprove / verify and ...
0
votes
1answer
307 views

Patch antenna excitation

How can we excite the patch antenna in different modes like TM10 and TM30? If a microstrip patch antenna resonates at TM10 mode can it resonate in other modes also like TM30?
1
vote
1answer
289 views

Why is the emitter current of a common emitter slightly greater than the collector current?

I'm trying understand where electricians came to agreement that Ie = Ib + Ic. I know that the base of a NPN transistor is very thin, allowing electrons to flow through to the collector which explains ...
1
vote
1answer
50 views

Signal reflections on conductors at low frequencies where they are not transmission lines

This question might be suited for the Electrical Engineering forum, but I think I might get more scientific explanation/discussion (rather than anecdotal) on this forum. Is the reflection phenomenon ...
2
votes
2answers
36 views

Why do the two relations of Power in a resistive load $P= I^2 R$ and $P = V^2/R$ (Assume Ideal resistances ) seem contradicting in this situation?

I have seen similar questions in the forum but they fail to be very specific . I would ask the question from the viewpoint of Problem Solving. Let me put this question from a textbook : A heater coil ...
5
votes
2answers
682 views

How come a mobile phone signal is blocked by aluminium foil, but Wi-Fi gets through?

Major puzzle for me. I have done a demonstration in lectures for years now, where I show that a mobile phone call can be blocked by wrapping the phone in a single sheet of standard Aluminium kitchen ...
1
vote
3answers
374 views

RC circuit discharge while being connected to a battery?

I am facing a conceptual problem in analyzing the following situation which was part of a physics exam: A series RC circuit with $R = 200k \Omega$ and $C = 10 \mu F$ is connected to a 5V battery and ...
5
votes
1answer
384 views

Why does my TV screen stay dust-free while other screens do not?

Recently I bought a pretty cheap flat-screen TV. Screen is IPS, semi-matte. 7 months now, I haven't cleaned it once, no dust at all. The TV works a few hours per day. I was wondering why it does not ...
0
votes
0answers
19 views

Do you get correct graph of transfer characteristic, if you take +ive Vds(constant) value instead of -ive. As mostly CNTFETs are p-chnl FET

I'm studying transfer characteristic curve of CNTFET to get value for mobility, S.S, etc. According to my basic background knowledge, NMOS curves lie in the 1st quadrant. While for PMOS they lie in ...
0
votes
0answers
22 views

Finding current through a branch in a multi-loop circuit

So I have the following circuit and I am supposed to find the current through the middle branch i.e., $I_{2}-I_{3}$. One way is to use the "loop current method". So using that I formulate ...
1
vote
0answers
21 views

How do Sources Affect the Linearity of a Circuit

How do voltage/current sources - both dependent and independent - affect the linearity of a circuit? To apply the superposition theorem, a circuit must be linear. As I understand it, this means that ...
0
votes
1answer
541 views

About The foxhole radio: coil rotation times, whether capacitor's needed

I recently tried to make a DIY foxhole radio. Althogh I made it according to the manual (140times coil rotated, ground(220V), blued razor blade, pencil core and antenna (just a steel stick about 1 ...
3
votes
1answer
6k views

How does a work function difference cause band bending in equilibrium in Metal-Oxide-Semiconductor (MOS)?

How does a work function difference cause band bending in equilibrium in Metal-Oxide-Semiconductor (MOS)? I don't understand the physical meaning behind this sentence from Sze: to accommodate the ...
1
vote
2answers
33 views

Why does an open ended wire cause the load to the oscillator to increase?

Using an ammeter between the wall and signal generator, I noticed that when the lead from a single channel is attached to the signal generator, the power into the signal generator increases by about ...
0
votes
0answers
22 views

What happens when supercapacitor is opened?

what happens to charge of a charged supercapacitor if the two electrodes are separated apart. do they still hold their charge if one electrode is discharged and placed back. does it get charged by ...
1
vote
2answers
85 views

How does a Zener Diode work as a voltage stabilizer?

I mean I do have this diagram though and all the stuff about how it works, but I read it and not all of it makes sense. In my notes it says that when the input voltage increases beyond a certain limit ...
1
vote
3answers
95 views

Could light erase a hard drive?

I have been having a theoretical discussion with a colleague at work. He proposed the idea of a laser being able to erase a hard drive. I know that a hard drive is basically a magnetic disc that can ...
68
votes
8answers
12k views

Why do fans spin backwards slightly after they (should) stop?

Today, I've decided to observe my PC fan as I shut the computer down. The fan slowly lost angular momentum over time. What I've found really interesting is the fact that the momentum vector change did ...
-2
votes
1answer
65 views

Why do they keep the street lights on in the morning? [closed]

I am sure that almost everyone at least once in their lifetime witnessed some street lights being on even in the morning. I wonder why they keep them on in the morning. Possible Explanations ...
0
votes
1answer
45 views

Voltage drop in a forward biased diode

I'm trying to understand why is there a voltage drop when a diode is in a forward bias. From what I understood the PN-junction creates a potential barrier of about 0.7 V for silicon. Now looking at ...
3
votes
2answers
153 views

Intuitive explanation: how does a LED work?

I'm looking for an intuitive explanation of how a LED works. I have a bachelor level understanding of math (I did take some physics courses as well, but nothing too advanced). I'll explain what I know ...
0
votes
2answers
59 views

How to calculate output resistance for a transistor in common base configuration?

This question more related to my physics practical than a theory question. How do i calculate output resistance if i have the corresponding table for it? I know Ro=...
-1
votes
1answer
58 views

Can electric signals be amplified in a simple circuit? [closed]

If a simple circuit is built with an DC source,an output resistor and an input source (I mean transformer or something through which signals can be passed through this circuit),will it work as an ...
0
votes
1answer
60 views

What are safe voltage differences to connect 2 batteries in parallel? [closed]

I have a OneWheel electric skateboard with a 58V LiFePO4 battery 130Wh (I believe 14s1p configuration). There is a method in practice where owners wire EGO LION battery packs (56v 2.5Ah=14s1p, 5Ah=...
-1
votes
3answers
62 views

Why are ultrasound devices using ultrasound? [closed]

I wonder why ultrasound devices are using ultrasound. Is it a biological reason due to our human audible range? Or is there a physical reason for that?
4
votes
3answers
1k views

Could we build a supercomputer out of wires and switches instead of a microchip?

I thought of this question; would too much wiring make a computer burn down? Or can you build an actual full-speed supercomputer computer using switches and wires? In other words, could simply adding ...

1
2 3 4 5
9