# Questions tagged [electrical-engineering]

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### 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 ...
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 ...
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 ...
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?
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 ...
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 ...
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 ...
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 ...
81 views

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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 =...
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 ...
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?!
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 ...
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?
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 ...
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 ...