Recent content by mickybob

You would need to use the permeability of free space rather than the permittivity, but otherwise yes.

From the man himself:

What I say below may be wrong, because for some reason this confuses me(!) but... First of all, I'm pretending there is no friction. In that case: If someone else is pulls the rope there is no mechanical advantage. They pull the rope by 1 metre, you move up by 1 metre. No problem. But when...

That document you posted doesn't provide a very good explanation, but they are correct about the ratios.

I've always found that having to write or explain something to someone else is one good way of making sure you understand it. Practicing solving problems is the other main way of doing it. The worst way is just to read it. If you're time-poor then I'd saying working on problems is the...

So you've got a rotating disk, and you're interesting in the centripetal acceleration acting on a point on the disk at distance r from the centre of rotation. For a given angular rotational frequency, the centripetal acceleration acting on the point is proportional to r, as your second...

Gravity is not a constraint force. The term 'constraint force' is used to describe forces that essentially act to impose boundary conditions. An example is the reaction force of the ground on you, stopping you falling through it. Generally these forces don't do work, since they don't act...

You missed out the third use, which is actually the use it's put to by the majority of graduates: 3. Putting you ahead of non-graduates in the queue for jobs which don't really require the skills and knowledge of your degree, but for which a degree has become the de facto entry requirement...

I'm not sure quite what you mean by 'continuous'. If you means that the light could be considered to be a perfect sine wave of infinite length, then the coherence length would also be infinitely long, so you would always see interference. In reality you can't have an infinite coherence length...

So what? The neutral is earthed at the substation instead in the UK. For the OPs question this makes no difference, the point is that neutral ~ OV.

If it's a floating system, it can be anything, see page 20 of: http://www.ussu.co.uk/ClubsSocieties/societies/stage-crew/Training%20Documens/L2+%20Electrical/REF%20BS7430%202011.pdf It's entirely irrelevant as everyone else is discussing mains supplies. I believe that, in the UK, the...

The Earth is often connected to the chassis of the device. If you did this with the neutral, it would - all else being equal - be okay. But now suppose there was a break in the neutral wire between the plug and the power supply. The neutral wire would jump up to 240 V and you've now got...

0V is an arbitrary concept, its only has meaning if things are tied to ground. Otherwise I could say the voltage of the live is 10000 V and the voltage of the neutral is 99760 V, giving a p.d. of 240 V. That is possible if it was a floating power supply.

The debate has got a bit side-tracked, so let's go back to the 'physics' of your question which I'm sure we'll all agree on. Firstly - please re-read my first post - I think you have some basic misunderstandings. 'Dangerous' means current flowing through you, not through a wire. You are...

You'd expect a small voltage drop, but 30 V seems pretty dangerously highly. Is that under load?