studiot

Yes a diode will prevent reverse current flowing. That is its function. Diodes used for protection like this are common. If the current draw is significant the ohmic heating effect in the diode can be significant as well. Generator is a generic term for dynamos (DC) and alternators (AC). Dynamos are significantly larger and heavier than alternators for the same current or power generation, because the alignment with the generating coil is only optimum for a short time. (This is actually almost the same effect as the question I asked you about ripple current and you declined to answer.)

Does it? And where would I find one?

That is what Bayes Theorem is all about.

Do you know what a singularity is and of any real world singularities?

Because magnetic monopoles have never been observed, even though they have been posited to exist. Modern permanent magnets certainly have much greater magnetic density than older materials. You haven't answered my question about current.

That is why cars have regulators and cutouts. They also have huge capacitors called automotive batteries. The ripple waveform is nothing like your picture. It is often a form of sawtooth. The current waveform is even more different and occurs as a series of short term pulses of very high current (do you understand why this must be so?) The 'bumps' may or may not be negligible, you would have to calculate that and you should be looking at the bumps in the current waveform more than the voltage. Polyphase generators are produced to reduce the height of the current pulse and the depth of the ripple sawtooth, becuase they reduce the time between current pulses. Google polyphase generators for lots of waveforms and specifications.

One should be careful about assigning a probability of 1 since its meaning may depend upon context. A) P(E) = 1 on an "a priori" basis implies that E has always occurred and must always occur. B) P(E) = 1 on an empirical basis means that means that E has always occurred (been observed to occur) but does not imply that E will occur in future - hence the common disclaimer in financial investment circles. C) P(E) = 1 on a subjective basis means that we may or may not have any data about past occurrences, but we think it will occur in the future, but this is not a guarantee like A.

I went for a holiday there once.

Cutworms and slugs having a party? Plant it rose end up about 4 inches (100mm) down and cover with soil. Traditionally this is done at Easter in the south of the UK. (I did mine about 2 weeks ago) My shoots have not yet started to show but I expect them soon. When the shoots grow to about 4 inches high cover with earth, leaving just the green tip showing. This is called earthing up. Keep doing this until your mound is about a foot of soil high. This is why potatos are known as a cleaning crop - you have to dig several times. Your potato looks like what are called maincrop rather than an early or new variety so harvest in July/August.

trumps mexican wave wall of course.

Whilst the ocurrence of a single midstream whirlpool is unlikely and the streamlines as drawn indicative more than anything else, I'm responding to the OP's idea that an immersed spinning body of fluid is subject to the same mechanics as any other spinning body, whilst noting the effect to be very small in the case offered. I also thought of tornados whilst I was reading it and then found he offered the same in his second post. I think it is a reasonable question, reasonably put.

Well done you. The process you are looking at is called chitting and relies on light to form the shoots. Potatoes don't grow roots in the light, they grow shoots. (Observation No 1) If the shoots are white there was not enough light. Most if not all the shoots are at one end, often more blunted / less pointy end. This is called the rose end.(Observation no 2). The roots will start to form in the dark, once planted. Obviously you plant the potato with the shoots pointing up. The potato contains enough food and mositure to start the growth going so roots are not needed initially. (conclusion no 1)

I am going to disagree with swansont here and state that the Magnus effect does indeed apply to your whirlpool, and to your tornado. A rotating body of fluid is called a vortex and Helmholtz first vortex theorem tells us that it can be considered a 'body'. So to answer you questions about what is going on. The generators of the whirlpool and the tornado are entirely different. Natural flowing water, of the type you describe, is not subject to appreciable temperature difference. Tornados, on the other hand, are thermally generated. Either way a laminarly flowing fluid does not suddently start rotating, there is always a causative agent (Kelvin's Law). In the case of open channel hydraulics this will be due to the shape and nature of the edges and bottom. Ther whirlpool will be caused by some static obstruction in the bottom (since you have placed it in the middle) or edges. Now the 'strength' of the vortex is low but it is constantly being reinforced by new passing water being swung round the obstruction so it stabilises at that point in the flow. This does indeed generate a transverse Magnus force. So why doesn't it move? Two reasons The rotational and flow speeds are actually quite low so the Magnus force is low. Not high enough to overcome bottom friction. Objects can be subject to a force but not move if another force, such as friction is acting. As already noted the vortex strength is low so any water that does separate and move off will quickly mix with the main flow. Note this vortex does not have (thermally induced) axial flow like the tornado. I think that analogies to electromagnetic field patterns are best avoided (even though this was also Helmholtz). Don't forget that EM fields have no material substance. This is an interaction between material bodies.

AC is AC and DC is DC. You will never obtain pure DC from an AC supply without an energy storage element in the rectification circuit. You would need an infinite number of phases to do this. This element is usually a capacitor. The output from any number of rectifying diodes is fluctuating DC, called ripple. This fluctuates above and below the desired output voltage. The energy storage element supplies the desired output when the rectifier output is below. Note below does not mean negative, just less than. Yes you can convert multiphase to single phase via a suitable transformer.

I would recommend that you tried to use your idea to explain proven phenomena before offering a speculation to explain a speculation. If you can achieve that, then is the time to move on to predict/explain new phenomena and see where that takes you.

Good, you may be able to get some of the data back then. Temporary files made by Office, for instance, are not locked. The process working its way through the list of files with certain extensions (jpg, doc etc) and making an encrypted copy. and then deleting the original. The orginal is not deleted immediately. So the original may be still there. If deleted it may not have been overwritten, which is the reason I said 'turn it off now', in which case the original may be recovered by an undelete program. But you must do this from another machine, the ransomware will not then run if the drive is slaved. As to removing the virus,that is usually not too bad, use combofix to kill any cloaking rootkit. Malwarebytes will rid you of the executable only, but there it has a recovery method. Good luck

Turn it off now. Can you 1) Find another pc to talk to us on 2) Do you have any backups or shadow copies. 3) Are you capable of removing the hard drive and looking at it from another system? 4) Sytem Restore won't help The encryption can't be broken, it is a damage limitation exercise. Sorry

No, I've never come across that one. Thank you. Yes I couldn't agree more, I've even started a thread here asking for examples of words which cause confusion because of multiple meanings in different disciplines. Thank you for the calculus example, I will add it to my list. I agree that truth is one such word, and therfore perhaps best avoided. Come now I think "just a convieniece is a bit weak", don't you? Well what of Euclid's 5th axiom then? It's logical to accept it and logical to reject it, but we don't have all this ho-hah about Euclidian v non Euclidian geometry. Both are equally accepted into mathematics as consistent. For the rest I think you are manufacturing an argument, where none exists. I made it perfectly plain that the mathematical statement "There exists an n such that n+2 = 3" doesn't give physical embodiment to the phrase "there exists", as does English, it actually means that n = 1 is consistent with the rules of arithmetic. By the same token the mathematical statement There exists an infinite object means that we can demonstrate a mathematical object which can be placed into one-to-one correspondence with a part of itself, that is not inconsistent with stated mathematical rules, though it may contravene others that we are not employing. It does not mean we can, as I said, buy a pound of it in Tescos. Sorry if you couldn't make that out. It referred to my previous sentence. Roughly translated I was saying Yes I assert that mathematical infinity exists, but on the other hand remember that mathematical infinity has a different meaning than the one you are perhaps used to in English.

Thanks for the interest ajb. I haven't seen the study itself, but It's really difficult to attribute causes to backgrounds. My daughter, (now a Doctor of Medicine) dropped maths after the A-S year (with an A* in the exam), in favour of French and German. She is more interested in people than Science. Her friend, a chinese girl from a family that ran a clothing business in Shanghai, not only managed straight A*s in double maths, chemistry and physics, but had to teach herself English at the same time, whilst living 6,000 miles form home and working Saturdays in a shop.

Glasgow University study. http://www.bbc.co.uk/news/education-36110880 This study made particular reference to developed countires and those where there is gender equality. The conclusion is that efforts to attract girls to science, techniology and maths have largely failed and that girls are more likely to suffer 'Maths Anxiety' than boys.

Of course it does. But equally of course The mathematical statement "there exists" does not mean you can go down to the supermarket and buy a pound of "infinity". It means that the properties of a mathematically defined object called "infinity" is consistent with the axioms and theorems already available. This is more in later with your later statement, which I agree with. However we should be aware that the words cardinal and ordinal have different usage in English and mathematics.

Up to this point I was not arguing. In fact I congratulated you on your correct reply to my first post in this thread. I was trying to show what happens when you put a minus sign infornt of the simplest possible fraction 1/1. And you got it right. So why change when the fraction becomes more complicated? There is no difference. I even offered a simple rule to follow, but you seem to have missed it.

You have posted this in homework help. It would help us greatly to provide a suitable response if we knew what the original homework question was that you are trying to answer. I can see from your two posts you are trying to put together physics that you have come across, so great encouragement for that, but unfortunately you are on the wrong track. Where do you think this 'centrifugal force' comes from?

Agreed. Either we multiply the top by -1 or the bottom by -1, but not both. In fact [math]\left( {\frac{{ - 1}}{{ - 1}}} \right) = 1[/math] Not -1 So using this fact we have if [math]\frac{{a - n}}{{a + n}} = 1*\frac{{a - n}}{{a + n}} = \frac{1}{1}*\frac{{a - n}}{{a + n}} = \left( {\frac{1}{1}} \right)*\frac{{\left( {a - n} \right)}}{{\left( {a + n} \right)}}[/math] Taking the negative and working both of the correct ways 1 and 2 in my post 10 Either (1) [math] - \frac{{a - n}}{{a + n}} = - 1*\frac{{a - n}}{{a + n}} = - \frac{1}{1}*\frac{{a - n}}{{a + n}} = - \left( {\frac{1}{1}} \right)*\frac{{\left( {a - n} \right)}}{{\left( {a + n} \right)}} = \frac{{\left( { - 1} \right)\left( {a - n} \right)}}{{\left( 1 \right)\left( {a + n} \right)}} = \frac{{ - a + n}}{{a + n}} = \frac{{n - a}}{{n + a}}[/math] Or (2) [math] - \frac{{a - n}}{{a + n}} = - 1*\frac{{a - n}}{{a + n}} = - \frac{1}{1}*\frac{{a - n}}{{a + n}} = - \left( {\frac{1}{1}} \right)*\frac{{\left( {a - n} \right)}}{{\left( {a + n} \right)}} = \frac{{\left( 1 \right)*\left( {a - n} \right)}}{{\left( { - 1} \right)\left( {a + n} \right)}} = \frac{{a - n}}{{ - a - n}}[/math] To show that this is the same as (1), multiply it by 1 and use tha fact that this is the same as multiplying by [math]\left( {\frac{{ - 1}}{{ - 1}}} \right)[/math] [math]\frac{{a - n}}{{ - a - n}} = 1*\frac{{a - n}}{{ - a - n}} = \left( {\frac{{ - 1}}{{ - 1}}} \right)\frac{{a - n}}{{ - a - n}} = \frac{{\left( { - 1} \right)*\left( {a - n} \right)}}{{\left( { - 1} \right)*\left( { - a - n} \right)}} = \frac{{n - a}}{{n + a}}[/math] Are you right now?

Trying it on something simpler is good advice. Look at this, there are ways of writing the number 1. [math]1 = \left( 1 \right) = \frac{1}{1} = \frac{{\left( 1 \right)}}{{\left( 1 \right)}} = \left( {\frac{1}{1}} \right)[/math] So if we put a minus sign in front we have -1 [math] - 1 = - \left( 1 \right) = - \frac{1}{1} = - \frac{{\left( 1 \right)}}{{\left( 1 \right)}} = - \left( {\frac{1}{1}} \right)[/math] Which ones of these are correct ? [math] - \left( {\frac{1}{1}} \right) = \left( {\frac{{ - 1}}{1}} \right)[/math] [math] - \left( {\frac{1}{1}} \right) = \left( {\frac{1}{{ - 1}}} \right)[/math] [math] - \left( {\frac{1}{1}} \right) = \left( {\frac{{ - 1}}{{ - 1}}} \right)[/math] None of these