Questions tagged [electrical-engineering]

The tag has no usage guidance.

Filter by
Sorted by
Tagged with
-2
votes
1answer
56 views

Bjt configuration

In common base configuration,we know that alpha is almost 1 which means that the base current is almost zero.But what is the physics behind this base current almost equal to 0?And similarly in common ...
-2
votes
1answer
53 views

Ohm's Law in Practise [closed]

When the AUX pin of a stereo is connected to my mobile phone's audio female port, I just measured the voltage at the end of this AUX pin (No load is connected) approximately 2mV using a DMM. But when ...
6
votes
3answers
2k views

Confusion about how an electron gun works

I'm a little unclear about the charge balance aspect of an electron gun. Referring to this diagram and similar diagrams I've seen, what I don't get is wouldn't the target of the electrons have to be ...
1
vote
1answer
71 views

Why we don't utilize most of the radio or microwave spectrum?

WiFi is from 2400-2500MHz or from 5000-5100. Fm Radio is 87-108Mhz, Phones : 450-3400Mhz But most of the spectrum is "wasted". For eg - Why we don't use above 5Ghz?
0
votes
1answer
137 views

Potential difference between two points

Okay so this might sound kinda stupid but I'm new to electrostatics and I was doing a question that asked me to find the potential difference between two points . Now I calculated the potential at the ...
0
votes
1answer
27 views

Electrical potential with a combination of bodies

1) what would occur with respect to electrical potential if a +1 charged body is brought close to a -2 charged body? 2) a positively charged body next to an earthed conductor For the 1st one I'm ...
0
votes
1answer
756 views

What happens to potential when a charged body is placed next to an uncharged conductor?

I know that the potential of the charged body decreases due to induction however I feel as though I need a more in depth answer. Why does induction cause the potential of the charged body to decrease ...
0
votes
1answer
40 views

Problem regarding phase difference in Transmission lines

In order to find impedence variation in Transmission line(T.L.) we usually draw Smith chart(it is a complex reflection coefficient ($\Gamma$) plane on which constant resistance and reactance circles ...
2
votes
1answer
81 views

Realistic for intelligent undergrad to build low cost muon scatter detector?

With a budget of under $2000USD, would it be possible for an undergrad student to build a muon scatter detector (drift tubes or another method)?
1
vote
1answer
56 views

Who controls completing the circuit in a transistor? [closed]

Consider an npn junction. The p-type semiconductor p has holes which are filled by electrons provided either by the n-type or by phosphorous dopants. The transfer of charge from n to p forms a ...
-1
votes
1answer
34 views

Alternator wear due to bad battery [closed]

I recently heard that a bad car battery (I assume "bad" means it drains faster than it was designed to) will wear out your alternator faster. How is this possible? Please note I am not looking for ...
0
votes
1answer
21 views

Piezoelctric Ceramic Transducing Capabilties

Piezoelectric ceramics are able to work as transducers, outputting electrical energy when mechanical stress is inputted. However, most ceramics have high static voltage and low current and power ...
1
vote
2answers
119 views

How does the centre tap of a **centre tap transformer** at zero volts?

As per my knowledge, the secodary coil will have one terminal at positive and another 0(zero) at one instant, and at another cycle, the other terminal becomes positive and the first one become 0(zero)....
0
votes
1answer
302 views

How does base-emitter voltage affect the current gain of a transistor?

I'm doing a Physics project related to transistor operation. My data shows that as the base-emitter voltage drop increases, the current gain of the transistor rises and eventually plateaus at a ...
0
votes
1answer
26 views

How does the charge on the battery terminal behave?

I am sitting in a train with a car battery of of twelve volts...its positive terminal is connected through a bulb to the metallic body of the coach which is connected to the rails underneath.how will ...
0
votes
2answers
34 views

Will the EM field radius of 10 x 20 Amp wires be smaller than a single 200 Amp wire?

Not sure how the radius is determined but Will 10X20amps wires in one conduit(meaning they are together) EMF radius be smaller than 1X200amps wire? I'm having a real life question on this: I can run ...
-2
votes
1answer
78 views

How can I negatively charge a metallic surface? [closed]

I wish to negatively charge the surface of a fan blade in a ceiling fan. As the fan is connected to AC power, it is safe to assume that we have electric power at our disposal. Also this surface needs ...
56
votes
3answers
9k views

Is there a physical limit to data transfer rate?

Is there a physical limit to data transfer rate (e.g. for USB $3.0$, this rate can be a few Gbit per second)? I am wondering if there is a physical law giving a fundamental limit to data transfer rate,...
1
vote
2answers
112 views

In the electrical circuit/fluid analogy is there an analogy for power loss across a fluid resistance?

For the fundamental passive $RLC$ electrical circuit, analogies are often used to describe the physics of fluid flow where $L$ represents the inertance analogous to inductance, $C$ is compliance ...
1
vote
1answer
23 views

Action at distance with charges (Electromagnetism) - help please!

My professor taught us in a theory lecture on electromagnetism , that if two charges are 1 light year apart and the charge on the left moves towards the charge on the right. The force felt on the ...
1
vote
1answer
364 views

Why is voltage gain highest in common base transistors whereas lowest in common collector transistors?

Although the common base transistors have current gain lowest and the common collector transistors have current gain highest.
0
votes
2answers
189 views

Most Effecient Railgun Design [closed]

This is my first post on this forum. My name is Kavika and I am a high school freshman. For a school project, I am designing and engineering a functional rail gun. I am on a budget and am wondering ...
4
votes
1answer
57 views

Different Color Intenensities from simple ON/OFF RGB subpixels

I recently got interested in electronic paper. One design that I liked was the one from Mirasol: https://en.wikipedia.org/wiki/Interferometric_modulator_display However, what I don't understand, is ...
0
votes
2answers
68 views

Circuit Analysis - Grounding and Current

Just starting to learn basic concepts of electronics, and I'm a bit confused looking at this diagram. Previously, we've always had a wire connected to the negative end of the terminal, and that made ...
1
vote
2answers
161 views

Reason for a thin base of transistor

I have been recently asked the following question: Why is the base of a transistor kept thin? MY ASSUMPTION Base is kept thin so that not many charge carriers could be neutralized in the process ...
2
votes
2answers
147 views

Science of Daisy-chaining [closed]

As everyone knows daisy-chaining power strips is very bad and dangerous. But could someone tell me why it's dangerous from a physics standpoint? (i.e. its effect on voltage, current, etc)
-1
votes
1answer
33 views

How computer knows how much charged battery is? [closed]

How does phones and laptops knows how much charged the battery is? I found lot's of simple devices like tv remote can also do that. Whats the mechanism behind that and does it vary with different ...
1
vote
1answer
46 views

Help with $I$-$V$ Characteristic of a Diode

I am struggling to understand why I can't get a full voltage range when I have the diode the correct way round. If you check this link: https://electronics.stackexchange.com/q/266201/ If you look at ...
1
vote
4answers
4k views

Why should a voltmeter have a higher resistance than of any circuit element across which the voltmeter is connected?

According to my textbook, it is said that, for an ammeter: It is essential that the resistance $R_A$ of the ammeter be very much smaller than other resistances in the circuit. Otherwise, the very ...
0
votes
1answer
75 views

Saturated BJT Transistors. V CE < V BE : AKA - Things that make you go “Hmmmm”

At the risk of being blasted for cross-posting, I am posting this question again here in the Physics department. It is a duplicate of this post in the EE forum. However, I would like to get some ...
0
votes
0answers
69 views

Saturated BJT Transistors. $V_{CE} < V_{BE}$ : AKA - Things that make you go “Hmmmm” [duplicate]

We use them every day and those in the know fully understand the functional characteristics of BJT transistors. There are documents and links galore explaining the operational math. There are even ...
-1
votes
1answer
36 views

Unknown $c$ in torque equations [closed]

In a book I have come across a couple of unrelated equations with an unknown $c$, in equations of the form $$T_{en} = \frac{P_{en}}{2\pi n_n}c,$$ where $T_{en}$ is torque, $P_{en}$ is rated power and $...
0
votes
2answers
54 views

Short Circuit Current [duplicate]

Theoretically, shouldn't there be no current flowing through a short circuit? Across the short circuit, the voltage is 0, and the resistance is ideally 0 as well. So how does it make sense for any ...
1
vote
0answers
45 views

How to determine the best fit battery for a battery powered application? [closed]

This is an attempt to get some scientific information about how to best use batteries (I'm going to refer to both single cells or assemblies of cells as batteries for the sake of this question) in ...
0
votes
1answer
50 views

Resistance of a Large (relative to lead contact) Conductor

How do I calculate the effective resistance of a large piece of metal between two small electrical contacts? The thermal image (from an interesting but unrelated article called An Exception to Ohm's ...
2
votes
0answers
40 views

What is the optimum altitude for tapping atmospheric charge?

The atmosphere appears to have a large potential difference (voltage) in relation to ground. The obvious example is the thunder where this voltage becomes large enough to break the insulator - air. Of ...
0
votes
1answer
162 views

How does a gate voltage determine the state of a transistor?

It is known that in a transistor, like the FET below, it has an 'on' state when current flows from source to drain, and an 'off' state when there is no current flowing between junctions. This current ...
0
votes
1answer
318 views

Minority charge carrier concentration in pn-junction during forward bias

my question: During forward biased, is it true that the minority concentration (e.g. hole in n-type) could be higher than the majority concentration of the same type (e.g. hole in p-type, which is ...
1
vote
2answers
2k views

How is it I can see the infrared Face ID on my iPhone X? [closed]

I’ve tried using Face ID in the dark on my new iPhone X and I can very clearly see the infrared flood Illuminator light up as well as the infrared dot projector. Is it possible for humans to see ...
0
votes
1answer
179 views

Why did Shockley's Copper Oxide Field Effect Transistor fail and has anybody succeed in creating a Copper as appose to Silicon based FET?

Reading Tomas Lee's very interesting historic account of Semiconductor's used in the Electronic industry: https://web.stanford.edu/class/archive/ee/ee214/ee214.1032/Handouts/HO2.pdf I wondered, why ...
2
votes
1answer
50 views

What happen to organic solar cell when applied electric field? [closed]

For example, I have a PTB7:PCBM organic solar cell. I applied electric field in forward basis. Will it contribute to increase charge separation? Then, if I do in reverse basis, what will happen to ...
2
votes
2answers
141 views

Why don't radio waves ruin electronics?

Out of curiosity, I estimated the voltage amplitude for typical visible light. Wikipedia says that sunlight hits the earth at about $1000 W / m^2$. The intensity of an electric field is given by $$I =...
3
votes
1answer
399 views

Power consumption of a qubit?

I keep hearing “A quantum computer will consume so much power that it'll need a dedicated power plant.” I'm trying to find literature to back this up. I would love to get an estimate for the ...
-2
votes
1answer
182 views

Equivalent resistance of a circuit [duplicate]

Can anyone help me with this one please?! I want to find the total resistance but the circuit seems neither parallel nor serie. What should I do?!
0
votes
1answer
58 views

What's a reasonable difference in resistance between batteries in parallel?

I know that the differences in resistance between batteries in a circuit will create different drop, and as a result draw unequally. Unfortunately, I couldn't get my hands on a parallel D-cell ...
0
votes
1answer
2k views

Use of slip rings and its working in a AC generator

What is the use of slip rings in an AC generator and its working? What would happen if there was no slip rings?
1
vote
1answer
370 views

Explaining the phsyics behind a coil gun

I made a coil gun for my extended essay, but I'm having some trouble explaining exactly how it works. The research question is how does varying the initial position of the projectile affect the ...
0
votes
1answer
85 views

Speed in telegraph equation

From the telegraph equation, it is found that electrical signals travel at fraction of light speed over transmission lines. For copper cables, the speed is about 0.5 c. Is such speed experimentally ...
1
vote
3answers
2k views

What are crystals used for in radio?

What are crystals used for in radio? I think I sort of know the answer to this but I would like a more detailed explanation. To my current understanding, piezoelectric crystals are used to modulate ...
0
votes
1answer
33 views

Can the telephone signals be tapped by an intruder? [closed]

I have a doubt. There are lots of telecommunication signals moving across the world, at the same time. For example, take the case of mobile phone calls. Millions of speech signals are propagating ...