# pulkit

Senior Members

660

1. ## Diff EQ help

A better way is to treat the variables x1 to xn as a column vector and get the derivative as a n cross 1 matrice then set it equal to the null matrice of same dimensions. Though in essence the same, it provides for a cleaner solution more appealing to the eye.
2. ## even and odd numbers

Do you have trimesters or two semesters ? The site said talked about 3 terms. I did a alot of what you mentioned, metric spaces, groups fields diverging into matrices. Also some part of multi variable calculus. But of course you have a lot more maths courses for obvious reasons. In all I had 2 in my first year. As much as it is posible to appreciate the beauty of the topics, I am sure glad I don't have to do them anymore, cs courses are about enough for me.
3. ## Electricity

Sparking in a plug occurs only because, beyond a certain voltage the air near the plug suffers from a dielectric breakdown or electric breakdown. Only once this has occured due to a sufficiently high electric field, does the air begin to conduct and hence you see a spark. The spark exsists only because the air is conducting. And the air conducts only because it was broken down due to high electric fields. I may be slightly wrong in point A of my previous post, but not completely. No charge accumulated 20,000 feet up in the air can cause dielectric breakdown of air near the ground, that will happen as the lighning passes down. I think Lance already mentioned that lightning moves in steps of 50 yards or so, that ought to explain what I just claimed.
4. ## Hydrogen Peroxide

Another way is to dissolve your iodide in some organic solvent likechloroform or carbon tetrachloride.That too releases iodine. But then you'd need to get the iodine out of solution, which I think may be possible by heating.
5. ## Silicon dioxide

Its a very interesting compound. One of the few in which the elements belong to the same group of the periodic table (These sort ofcompounds are always interesting -- inter halogen compounds par exemple) . SiC has both structural and physical similarities to diamonds. Its crystal structure is 3-d with both Si and C involved in a complex 3-d matrice, like diamond. It is used extensively in making tools because of its hardness. It has interesting properties also becaues of its part organic nature - which is why it dissolves in organic reagents like carbon tetra chloride.
6. ## Hydrogen Peroxide

A reaction between iodide and iodate under acidic conditions (HCl would do nicely) would release iodine. If you already have iodide, then a lot of the problem is solved. Iodate shouldn't be hard to get hold of as its quite a cheap reagent.
7. ## Fahrenhalf Degrees

While on the topic of temperature scales, there is yet another one worth mention called the Reaumur scale which took the freezing point and boiling point of water as reference, just that it assigned value 0 to freezing point and value 80 to boiling point.
8. ## Fahrenhalf Degrees

Given that blood is an aqueous solution, its boiling point would be elevated from that of water. In other words I don't think blood will boil at 200 frht but a some temperature in excess of 212 frht. Also fharenheit scale is not based on freezing and boiling point of blood. I don't think people are insane enough to do that sort of stuff. It won't add a human touch to the scale, only add a touch of disust to it. 0 frht is the temperature at which an equal mixture of ice and salt melts. 96 was the normal blood temperature -also it was initially caliberated using horse blood and not hman blood. These caliberations done by him were not so accurate and were later changed.

What happened to Fred afterwards ? Was he left fit for consumption ?
10. ## Electricity

A) Air will only ionise once lightning has passed through it and not before that. B) Once air breaks down electricity, it will offer next no resistance to flow of charge C) Distilled water is a very bad conductor, in practical situations water will have a much larger conductance.
11. ## Tesla Coil

Not so sure what a Tesla coil is. Is it a metallic loop in which no magnetic field may exsist ? I mean is it like a magnetic analogue of a Faraday cage ?
12. ## Silicon dioxide

SiC Silicon carbide they share 4 electrons each. One of the hardest substances known to man, hardness close to that of diamonds.
13. ## Electricity

Man in pool would actually stick out as an easy target so to say for lightning. You must also take into account that water has very high resistance and a pool of water might as well offer more resistance than a man. I for one wouldn't stay inside a lake or a pool during a thunderstorm )
14. ## Silicon dioxide

and exactly how does SiF4 prevent that ? As mentioned H2SiF6 is formed as SiF4 disolves.

I think there is another factor to investigated here. The fact that a sharper object would have more chances of "catching" a lightning bolt - I say this because almost always those things on buildings are made sharp, thick and metallic. I don't fully understand why this happens. The only thing close it that I have studied is something called "corona discharge" whereby sharper objects tend to be able to discharge static electricity more easily than less sharp ones. Does this sharpness have anything to do with the situation in consideration ?
16. ## Science Web Sites

http://www.particleadventure.com Go to this place if you want to learn particle physics.

There is a difference here. When you talk of lightning, you are not in parellel with the pole. The circuit connections so to say have not been made yet. In this case there is a choice whether to travel through circuit (not branch) A which would involve going down a pole or through circuit B which would involve going down a human. The fact of the matter is that a parellel circuit will only be achieved if you are touching both the ground as well as the pole. Now there is no choice of circuits to pass through, you become a single circuit with a net effective resistance. As far as parellel circuits are concerned, electricity does not ¨choose¨ its path, but it divides accordingly. The closest you can get to ¨choosing¨ is when you short circuit an element.
18. ## Silicon dioxide

[MATH]SiF_4[/MATH] is the corrosion product itself. Once it has been formed, your glass has already melted away. It does not form a protective layer like aluminium oxide would over aluminium, and will not prevent further corrosion.
19. ## Electricity

Not necessarily safe. Open circuit means vacuum and not air. You see lightening only because the electric field generated is so enormous that it causes the electric breakdown of air. Air like any other substance a limit beyond which it will break down. Once this limiting field is surpassed, air starts to conduct. Now if you have a can, it is obviously not safe, the air itself is now conducting,so you actualy have a closed circuit and not an open one.
20. ## even and odd numbers

Yes its a nice topic. The fact is that it has a lot of applications in computer sciences which also why we had to do it. Its used in all sorts of places like data mining and algorithm optimization. I think one of the fastest known multiplication algorithms uses metric spaces - but thats still too complex for me to understand yet. We actually diverged to multi variable calculus towards the end of the course as well as all the stuff with Taylor and McLauren series and then weird types of integration stuff - all that I am pretty sure won't be of any use to me later on (perhaps only the Taylor series part may be useful).
21. ## an asymptotes problem

Or you could try [MATH]y=e^{\frac{1}{x^2-4x+3}}[/MATH] or [MATH]y^{x^2-4x+3}=e[/MATH] In fact you could replace e by any positive constant greater than unity.
22. ## Fahrenhalf Degrees

You would do well to make some of the electro magnetic constants dimensionless. I find the SI system quite bugging when it comes to finding out dimnesions of quantities like magnetic field and magnetic flux. Things start to become very complicated and you have to look at specific definitions of field to relate it to electric current. It would be usefull if constants like magnetic permeability were indeed dimensionless. Also some units like Coulomb are quite useless practicallybecause of their enormous size. You almost never encounter charges of the order of a coulomb. How does the new unit of charge scale with respect to the coulomb ? I think t comes out as 0.16 coulombs which is still pretty high. The same arguement also applies to magnetic flux density, wherein you rarely encounter densities in tens of Teslas, mostly they are fractions of a Tesla.
23. ## Fahrenhalf Degrees

Another point that I'd like to add is that often when such natural units are introduced, not only is the value of certain constants set to one but also they are made dimensionless constants. This is where sometimes these units gets tricky, because some of the more common quantities then acquire new dimensions. But if you look at it in the absolute sense, this dimensionless business is also helping to simplify things. You have to worry about less and less units. For eg. Most people won't be able to write down the dimensions of a quantity like epsilon not in the SI units within a couple of seconds, ask them to do the same within some other appropriate natural system and its done in no time.
24. ## Lighter cars.

Given engine technology today, lighter would only mean faster. Faster cars provided to people may not be a good idea, the speeds may increase so much they might nullify affect of any new materials used.
25. ## Silicon dioxide

Changed it to [MATH]SiF_4[/MATH] , wrote [MATH]SiF_6[/MATH] by mistake. Whats anionic now ?
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