Engineering

I have an electronics test tomorrow, and I got most the the theory down, but if we quickly consider a N type mosfet with a positive Vgs is applied, the positive holes in the P-type channel are repelled, thus the area becomes negatively charged (or is it more accurate to say electrons are attracted to the area??), but this does not necessarily mean there are free electrons to carry the current does it? Where do the charge carriers come from? I watch a youtube video that says electrons are attracted to the region, which doesn't make sense after the channel has been negatively charged, since it will repel electrons. Thanks in advance!

I know there are cloud seeding technologies already but for me that's sh*t. Will we one day we able to control every aspect of weather all over the planet? Like controlling what temperature we want to have, how much rain and when/where should it fall, how much UV we want etc. Coruscant from Star Wars (a gargantuan planet-sized multi-level megalopolis) had such a system. Personally I would like to see nice 20 degree Celsius weather in Sahara year round.

If we placed some conducting coils inside a magnetic field created by 2 permanent magnets, Ampere's law tells us that the current in those coil will be proportional to the flux flowing through the coils. This is fine if the coil is a super conductor, but as soon as you add a resistor to the coils, the current will create a potential across the resistor and thus the coils. Faraday's law tells us this will produce a changing flux, in this case the flux in the core will reduce. This seems to lead to an odd conclusion, either the permanent magnet strength must decrease to reduce the flux or the core must become extremely resistant to flux at steady state. My money is …

The resistance of the source and inductor are set to 0, this must be a mistake right? I was expecting current to stay constant after the source stops pulsing.

A problem with wind turbines is, of course, that their power is intermittent. I have seen talk of using compressed air or batteries to store the power but both these solutions have problems with efficiency, and batteries leak power even when not used. I was thinking, what about using a heavy weight to store power? Electric motors would lift a weight, then when power was needed, the weight would fall, running the motors backwards and generating power. I guess it would be very efficient, and there would be no leakage of power even if the stored energy was not used for months or even years. It is low-tech and very low maintenance. The heavier the weight, the less fa…

Anybody can tell you that if you wrap some wires around a something then pass a current though it, you will make an electromagnet, but did a single one of you stop to consider what was actually going on? Faraday's Law tells us that is we apply a voltage to this coil, the flux within the coil will increase with time. Consider a voltage being applied directly to a coil, well this should produce a ever increasing strength magnet right? But we know that DC electromagnets create a constant strength magnet. I sure as hell haven't heard of somebody creating some kind of magnetic singularity in their basement. So who can tell me why a DC electromagnet creates a c…

How I can declutch an electric actuator ?

How do you prevent eddy currents in a transformer? (I know the answer, just testing you guys).

Hi all, just registered to see what people thought of this idea. I believe the latest problem is that the containment pits have cracked, allowing contaminated water to leak into the sea. Why not use gelatine to turn the contaminated water to jelly and reduce how penetrating it is? It may also reduce evaporation If this seems reasonable, how can we get the message to tepco?

So I understand how the rotating magnetic field is created in the stator, so lets assume we have a uniform intensity rotating magnetic field and work from there. Lets start from a stationary position. The flux lines from the stator magnetic field cut the squirrel cage bars, inducing current and thus inducing a north and south pole in the rotor. This induced 'magnet' attempts to align with the rotating stator field, but as it approaches the stator magnetic field rotation speed (synchronous speed) flux line cut the bars less often, thus less current and a weaker magnetic field induced by the rotor. This is why the rotor speed never quite reaches the synchronous speed si…

To live in a flying city would be truly amazing, but how would we make it fly, power it, and control it?

Hi. What tough 'clear-to-heat' plastic film permanently exposed to sun, rain, wind (no snow) would you suggest ? Something similar to polyethylene. It is to cover a coil of black HDPE as for a solar water heater, shielding it from cooling winds and letting sun heat pass trough ? A life of 5+ year would be desirable. Greenhouse cover or there is something better ? A coil similar to this attachment, placed on top of a suitable heat insulating polyestyrene foam sheet, and covered by such film instead of glass or polycarbonate sheets.

I am teaching Bioprocess Engineering lecture but the lab of my school does not have many instruments and equipments. With basic equipment(without a bioreactor etc) bioprocess experiments for students that we can follow the process every week. I need some cool and interesting ideas..

Hi! I need an efficient power supply for my engineering activity. I have several variants but more keep to this isolated dc dc power supply. What supply will you recommend?

Those medieval castles with massive stone walls and in general, huge loads on soils, how were their foundations 'calculated', in ages with little tools, expertise, no reinforcing bars, portland cement, soils testing and engineering ? Many still standing, built with handcrafted and selected stones, erected with great efforts. Building sites mostly on solid grounds, but not all of them. Deterioration trough 4-5-6+ centuries show above ground, but, how good are their foundations after time elapsed ? How was that success achieved then ? The names and techniques of the engineers forgotten, the owners are the famous. ----> https://duckduckgo.com/?q=medieval+ca…

Hello Why newton's third law is not applicable for non-solid subsatances....?

What is the strongest diving suit available? How much PSI can it take under the sea?

Hello All, Long time reader, first time poster. Not an engineer. Problem: A car drives over a speed bump. How much weight rolls over the speed bump per axle? Assumptions: Normal sedan, suspension, tires, etc.; weighs 3000lbs Assume 50/50 weight distribution (I know it's not) Driving 10mph Speed bump is 1ft long, 1in high (I know, small) Questions: What would your thought process be? Please be detailed. What's the right unit of measurement? lbs/square inch? Considerations / missing information? Thinking the suspension might come into play... anything else? What would some good assumptions be? Note: This is not a work or academic related problem-- Jus…

If the electrics were to have battery/caps in various standard sizes, and those standard sizes were available for replacement in an exchange system at charging stations, then a fully charged battery/cap could be quickly installed, the old battery/cap traded in and recharged for later testing and resale. This could be done in no more time than to add gas at a traditional gas station. On a high amperage quick disconnect, the lighter batteries for compacts could be exchanged by the customers in most cases. Larger vehicles would have bigger, heavier units to exchange and be priced accordingly. Another possibility is to offer charging stations a subsidized solar/wind utility …

Several companies or administrations develop fast neutron reactors presently, one project being Astrid by France's CEA... Well, these reactors are perfect targets for present-day weapons. Take for instance a 20t single-stage solid rocket that fits on a banal truck - simpler than a V2. It can propel a 2.5t passive steel head out of the atmosphere to 2,500km range where the head falls down at 5km/s. This pierces some 5m steel or 10m concrete - thicker than any present or future reactor can have. The recent Chinese anti-airplane-carrier-missile may be of this type; anyway, it punches a ship that is better armoured than a nuclear reactor. Falling on a reactor, the hea…

ok in conventional coal power plants we lost large amount of heat (35%) when steam condensation to water, why don't we just send stream back in to furnace without condense in to water more fuel save

Hey all, Basic question here. I'm a noob starting out with electronics and I've had a hard time getting an answer to the question this topic poses. I've got a basic electronics project I'm putting together: I have a small wind turbine I've put together that generates some electricity. I also have a small solar panel I'd like to wire into this circuit to basically add to my total output and charge a small battery. What would be the best way to go about this? I've heard that charging from multiple sources of varying voltage can be bad, this will obviously be the case considering the wind turbine will not always be spinning and the solar panel will not always be rece…

I have question here :Suppose that I build anti-gravity vehicle,is it possible to move that vehicle in earth atmosphere or in space: 1. By using earth electromagnetism 2. By using universe electromagnetism or other universe forces.

Im a pretty serious musician i think and was wondering if anyone out there could help me out i use some chapstick (lipbalm) and i put it on very edge of the last fret of my fret board (mainly the last string) so i was wondering does anyone know if the molocules can grab ahold of the string too cool the string down? It does certinaly help, so i was wondering if any1 could give me some ideas if this does work or not or if im just full of my self haha thanks

Is it possible to turn on the tap so that lots of water flows down and then put a piezoelectric crystal under it to generate power?