Engineering

It's like a laser connected to a radio or something. The lasers oscillate at frequencies that you control using the radio tuner. The laser makes cool pictures, including stars, circles, swirlies, squares, zig zags, etc.

I had read an article about a large microwave cavity but cannot find the dimensions of the room, it isn't available online. http://web.mit.edu/giving/spectrum/spring02/hands-on-learning.html I want to calculate the approximate frequency generated by the cavity and wonder if anyone has the dimensions for Room 26-100? I have heard that amateur radio "microwave" enthusiasts have sometimes turned metal silos into microwave cavities. Microwave is sort of a misnomer as the MIT room cavity could be in the low high frequency range. Does anybody know of other examples of "large" microwave cavities?

I was wondering: How easy would it be to make a radio at home with common materials? And how cheap? This radio would cover as many frequencies as possible... And please, I don't know a lot of the things like "Use a ___ resistor," I'm not that much of an electronics person.

As mentioned in the topic thx

in airplanes, what are verical and horizontal stabilizers for? is it only for changing direction with elevators and a rudder, or can they do something that the wings can't?

Just something I was thinking about: First, the car's an automatic. Don't know if that matters or not. Second, like all cars, it moves forward (albeit slow) when in drive and you're not touching either the gas or brake pedels. Third, this is assumably because the engine is turning and thus the axel and wheels turn. Fouth, when on a hill of certain incline, the car doesn't move either forward or backwards despite it being in drive and niether the gas or brake pedels are being touched. So, if the engine is turning the axel on the level ground, how does it not turn it on the incline? The engine has to be turning something. It can't know when it's sitting on a hi…

I need help with a question and wonder if anyone can point me in the right direction. Two capacitors of 20 microfarad's and 40 microfarad's are connected in series. A constant voltage of 50 V is applied to the combination, it is then removed and replaced with a short circuit. Determine the final charge on each capacitor ?

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Suppose we have a Aluminium on p-Si wafer contact. Calculations have shown that it will form a Schottky junction since the p-doping will move the fermi level towards the valence band, and hence the fermi level of the p-Si before contact will be lower than the fermi level of Al before contact (condition for a Schottky contact for metal-semiconductor). In a non-ideal contact, a thin insulating layer of Si oxide is between such contacts. If the applied voltage with respect to the Si-wafer is 10V, estimate the amount of field-assisted emission current. Also estimate the amount of the tunnleling current. Given that the thickness of the SiO2 layer is (i) 2nm. (ii) 1…

Well, it just so happens that white tail deer archery season is now open in Wisconsin. And with this season come the old wives' tales of the inbred hillbilly emptying the shot from a 20 gauge shotgun shell and firing an arrow in its stead. Well, after pondering this story I decided that a pneumatic arrow launcher would be the way to go.

I'm working on a tribological problem involving a MoS2 coating, molybdenite, but am having a problem finding a suitable value for its elastic modulus (Young's modulus). Anyone got any insight ?

I need some information or guide on how i would create a varaible voltage power supply based on LM317L, the voltage should be adjustable from 1.2 to 12 volts by using the potentimeter build into the breadboard, To test this cruit i have to use a 12 volt 960mW lamp. Thanks

Recently, I was searching through the internet, and I came across a rather strange invention. It is called the O-Zone Lite. (http://www.ozonelite.com/) It claims to kill airborn bacteria, mites, and other nasties like pollen. According to popular science it oxidizes air. How does it do that? NOS? Ozone? Im still skeptical at this point, mainly because if it releases Ozone, then I would avoid this at all costs, but if it truly is safe, and affective at killing the airborn critters, then it might be worth buying.

Tesla coils often enter conversations but so far [i searched for it anyway] i cant see an official tesla coil thread. so i though't i'd start one.... people can learn about making them... post pictures of currently made and working ones and so on and so forth. i was thinking of making one [my first one] and was wondering for some pictures of others and just general advice and stuff!

I wonder in cellular communications, the base station obtained the desired signal from a mobile user from multipath effects, so that Doppler effect due to motion of user and reflection of radio waves by barriers causes a certain amount of interference since different radio rays are not exactly in the same phase as each other. How does the receiver end decode such signals at the demodulation stage? How can demodulator be so smart to decode such signals with so much interference?

What do you actually mean by thermal equilibrium? From what I know, a system in thermal equilbibrium cannot do external work or else it will violate the 2nd law of thermodynamics. And why do we always use Boltzmann statistic to model and derive so many semiconductor equations?

Hmmh. I don't really know where I should put this, could even put it in the GD, put since it has to do with... err, electronics and gadgets, after about 5 seconds of careful consideration, I put this here. Sooo... I've been going to buy a Geiger counter for a long time, and now I'm thinking which model is the best. It would be used to monitor quite low levels of radiation (operating range from 0.01uSv/h to 1mSv/h maybe). A digital display wouldn't hurt either. I have considered the Inspector-model: http://www.geigercounters.com/SpecInsp.htm (you can even buy a nice piece of software for it ) Any better suggestions?

In most modern aircraft the cabin is pressurized. Despite this you still get the caracteristic (and often painful on descent) ear popping. Why does the pressure change when it is meant to be a controlled environment?

I have recently come to know that information can be much faster than light Information takes a few moments to travel from one corner of the universe to the other. Previously I was of the view that light is the fastest thing in the world. Can amy one explain this?

As stated in the question, to me, both actually study the same thing.... What extent do they study differently? Albert

Hey, just wondering if atlantis is possible, and where it may have been or is still, if it comes to it..Scientifically possible?

2 identical pices of steel wire of equal length were used to manufacture two springs. Diameter of the first spring coil was d, diameter of the second was 2d. Both springs were then loaded with the equal masses. As a result, the first spring stretched out to the one tenth of its initial length. What was the percent elongation of the second spring? Any of you genuises know how to solve this question Hope i put it in the rite section.

Ok, so my friend and I finally got a boat running the other day, old 75 hp 2 stroke mercruiser. Its a quick boat, but man is it nasty. Anyhow, getting out on the water, cruising around in the boat has got me thinking. I'd like to understand more about how boats propel themselves through the water. His is a typical outboard engine, prop, etc. One thing I'd like to know is how to determine how much prop size will effect acceleration, top speed, etc? Basically, I'm wanting to learn alot about boats, as we are now thinking of trying to build a custom boat, I need to learn some stuff. Any info would be appreciated.

http://www.popsci.com/popsci/science/article/0,20967,676853,00.html Hey, waddaya think about this bit here?

Switches, on and off... and stuff. Is there a site where you could learn about different switches (since I'm sort of an engineering/electronics newbie)? I have basic information about reed and mercury switches, but some more complex ones maybe? Please share information about unusual switches.