TonyMcC

Did you mean "tune an INDUCTOR (or capacitor)"? A crystal is usually accurately cut to oscillate at a given frequency or one of its harmonics. That manufactured frequency can be changed a certain amount with a tuned circuit - but only by so much. The resonant frequency of a tuned circuit is 1/(2*pi*(SQR(L*C))) Hz. I have never experienced an oscillator circuit that was tuned to a different frequency by changing resistance.

Astronauts in the space station drink recycled urine and according to the link it is cleaner than American tap water. http://www.usatoday.com/tech/science/space/2008-05-14-spacewater_N.htm

The point I made is that the face is not perfectly symmetrical and the image in a mirror is reversed left to right when compared to actuality. To take an extreme example, if by some unfortunate chance you had lost your left ear the image in the mirror would lose its right ear although a photo would show you had lost your left ear. So, as I understand it, the answer to the OP's question is "Yes there would be a significant difference".

You are correct in saying the electrical properties of rubber varies. Therefore your question cannot be properly answered. If you Google "electrical resistivity and conductivity" you will soon find some facts and figures including those for hard rubber. I basically agree with moontanman with one exception. He should have said voltage where he says amps. Using the water analogy, where pressure represents voltage and water flow represents electrical current in amps, it is the pressure in a water pipe that might burst it and not the flow of current through it. Similarly it is the voltage difference across an insulator that might cause it to break down, not the current through an insulated conductor.

Its complicated, but I think you mean its shape will be defined by Fourier analysis of the frequencies that together give the pulse its shape? I agree that the number of pulses per second is properly called pulse repetition frequency (prf) although this is commonly described as the frequency of the pulse train.

I suppose the following is possible. Man has, or will soon have, the intelligence and ability to create a black hole. The black hole could rapidly grow sucking in the earth. This might only be the start because as it grows it may suck in more and more matter and eventually suck in the whole universe. The singularity within the black hole could create a big bang and be the start of creating a new universe. This may already have happened a number of times and our universe could be just the latest in a chain of universes. Thus this and previous universes could have been created by intelligent, if rather stupid, beings. As had been said before - all things are possible!

If you imagine a vertical line dividing your face into two halves then the two halves will, in almost every case, be unbalanced to some extent. You can get some idea of this by holding a sheet of card that covers half your face and looking in a mirror then repeating with the other side of your face. This why you always feel that there is something "strange" about photos of your face.

I find no problem with Google. You can ignore its suggestions and continue typing until you have completed your intended entry. If what you want appears early so that you can click on it before completing your entry then I see that as a bonus. If you misspell something it will give you choices using the correct spelling. If your word(s) was unusual but in fact spelt correctly you can tell it to search the word(s) you entered. I must admit that in my case I do quite often spell words incorrectly and so quite like this feature. Long Live Google!

I don't know about 1 being flawed, but it certainly is peculiar in that 1^n=1 and 1^(1/n)=1. Thus the number 1 might in fact represent a square, a cube, square root or a cube root. I have an interest in Fermat's last Theorem and this fact has always given me something of a problem.

You may get away with it if the motor is not under load as its speed of rotation may produce enough back emf to limit the current taken to a safe level. Once under load and its speed of rotation decreases it will draw extra current from the battery and there is a risk of damaging the motor. I would not expect to find any component to be fed with a voltage greater than its rated voltage in any commercial product. There are conditions where your battery may not damage your motor. For example the battery internal resistance may be high enough to limit the battery terminal voltage to<4.5 volts under load conditions. But its not a good idea to rely on this - an old battery could be ok, but a new battery could cause damage. Also there is the question of insulation of the windings etc. - although at these low voltages its probably not a problem.

I think it is theoretically possible. However, at the frequencies involved the power loss becomes enormous over relatively short distances. Also the radiation emitted will be a health risk to anyone near the transmitter. Overall it is probably not a good idea (IMO). There is a good reason why the window of a microwave oven has some sort of mesh over it.

Not sure what you are after but a magnetron is a fixed frequency oscillator. It can be pulsed on and off but you can't modulate its frequency.

Marat - Before I begin I must make clear that I am just a fairly old chap with quite a lot of experience of life and absolutely no experience that parallels yours. Please feel free to think me a silly old fool if I am way off the mark or, if there is truth in my observations, a sort of Granddad figure. You seem to me to be a compassionate, caring and sensitive person. I wonder whether your admirable traits of compassion and caring have led you into a sphere of experience where compassion and caring are certainly needed. Also there is merit in trying to work out some way to negate the suffering you have had to work with. However I feel that your experiences have given your sensitive side such a battering that you have become unable to see the wider picture of the sort of life that most people experience. To use an analogy we are all born with a hand that we can play in the game of life. The hands are not equal in strength and some people get such a raw deal that life may not be worth living. Although this is a sad and undeniable fact, for the vast majority of people the hand they are dealt at birth is well worth playing. Most people, in my experience, are glad that they were born, enjoy life ,accept as a fact that one day they will die and just hope that death will come peacefully in old age. I am not experienced in any medical matters but I do wonder if your experiences have left you clinically depressed. You would be in a better position than I to consider that possibility. There is an old prayer( which contains good advice for anyone) that you have probably seen before. I hope I haven't offended you. God, grant me the serenity to accept those things I cannot change; The courage to change those things I can; And the wisdom to know the difference.

Looks like the US government is worried about this. From today's News:-

On reflection I have to agree that putting my greatgranddaughter's picture on the web was unwise. I don't know how to remove a post, so if someone could advise me or perhaps a moderator could remove it for me then I would be grateful. Thank you Michel and Spyman for your advice.

My ISP (TalkTalk) has recently introduced computer protection called Homesafe. It attempts to block viruses before they get to your computer. They still advise you run your own AV as well. Because the software is not held on your computer there cannot be a conflict problem. I have often wondered why ISPs didn't provide something like this because if perfected we would not need AV programs. Edit-

This is a member of my family 3 generations from me. I don't believe anyone can look her in the eye and say "You would be better off dead". I don't believe any prospective parent would not be delighted to have such a child. Would you really advise me to persuade her parents to painlessly end her life to spare her from the imagined "horrors yet to come"?

The man was blind and reading text formed using braille . Later edit (I don't know how to set up a "Spoiler" - just looked at Imatfaal who seems to agree with me - I'd appreciate advice on this) . Later still edit - Found how to do this under "help".

I cannot understand the popularity of "shoot 'em up" types of computer game.

Marat - None of us chose to be born and all of us must die. It is best to accept these as facts and make the best use of what lies between - because basically that is all there is for each of us, at least in this world. Since we don't really have a choice in the matter we might as well enjoy what gives us satisfaction and pleasure and accept that life will throw at us disappointment and pain from time to time. That is the nature of life and in my experience, as a man in my 70's, most people do not dwell unduly on possible misfortunes that may or may not lie ahead. Perhaps one day when you are in your 80's you will walk round a corner and be zapped by a stroke of lightning which will kill you in an instant! If something like that happens what benefit will you have obtained by a lifetime of dark thoughts concerning suffering and death?

I'm not really sure what you are looking for. But, it is realatively easy to do addition when the two numbers to be added are both binary numbers. The rule is simply 1+0=1 and:- 1+1=0 and carry 1 Just work your way from right to left. You will find that you will generate a carry for the first two rows when you add 1 to 10011.

I believe some cars have active noise cancellation. If you google - cars active noise cancellation - you will get quite a lot of information. Off the top of my head I would suggest that one problem would be the ,admittedly short, time needed to process the unwanted noise and output the same in anti-phase.

How about a similar system using satellites like a car's satnav? I feel my satnav gives a more accurate indication of speed than my speedometer. Just realised that this would indicate speed over the ground and not airspeed!

I agree with you. In fact I wouldn't really expect anyone to convert any motor designed to rotate in one direction into a reversible motor. However, as this was a homework question, I thought it not a bad idea to say that such a thing was (theoretically) possible. I then mentioned that if all else fails you can buy a reversible motor. I hoped that "if all else fails" would be taken as "having thought about it".

It is quite possible to have reversible ac motors. One type is similar to a dc motor, except the magnetic field is produced by an alternating magnetic field instead of a permanent magnet. You can work out how to reverse such a motor. Another type uses a capacitor to produce phase shift which means the rotor can be fed with an overall rotating magnetic field which a sqirrel cage can follow. You can work out how the field rotation could be reversed. If all else fails then it is possible to buy reversible ac motors. http://www.orientalmotor.com/products/ac-motors/