advertisement


Electricity Doesn't Flow Through Wire

chartz said:
Ok, so what does screening do and does it have the slighted effect?
Click to expand...

Do you mean as in coaxial cable? Or some other context?

In general it is making an arrangement that confines and/or excluded EM fields from reaching specific places. So in co-ax it is the effect of having an outer 'cylinder' of conductor to prevent either the now-internal EM fields extending outside the cable, or external EM getting into the cable.

Note that using metal for this purpose makes some assumptions which often go unstated, and may not always be met! So details *may* matter depending on the circumstances.
 
Colin L said:
Ian Jack has described the teaching of physical processes and systems taught up to A level as “lies to children”. They are given a superficial understanding but actually the way things actually work is can more gnarly, complicated and counter-intuitive than can be easily understood.

On the other hand, Feynman’s view was that you don’t truly understand complex systems unless you can explain them in simple terms to a non-specialist.
Click to expand...

Not so much complicated, I'd say, as counter-intuative. Made worse in the end by the simplifications often adopted to 'get by' at earlier stages of education when they aren't warned that they *are* simplifications, so make assumptions that aren't always appropriate in practice. In fact essentially *all* science is provisional at one level or another. So has to be used as evidence has show to be appropriate. Fundamentla research is all about looking for the quirks where present ideas may not 'work' as ways to understand things. Alas, some theoriticians use that to dream up really crazy ideas! ... sometimes so bonkers that they turn out to work! 8-]

BTW one ot aims of the upgraded systems at CERN is apparently to have a jab at looking for the "5th force"... which will be interesting.

Alas, I can't say I'm a fan of his textbooks. Despite the above they seem to me to assume a lot on the part of the student.
 
IanW said:
Feynman is a great person to watch and listen to. His simple explanations do make it easier to understand how complex systems work.
Click to expand...

Yes and no. He was a great talker, and makes people feel they understand as they listen and he draws on the board. But later on when they read the notes, etc, they may find he skipped things which puzzle them. He was a great showman, as well as a joker. He *could* sell salt. 8-]

So in the end the effect of his lectures tends to rely on the students being smarter than they might realise.
 
John Phillips said:
That's a technique I use. Even to the extent of trying to explain something to my own uneducated former self in a few simple paragraphs. I find it does expose flaws in my own understanding that I can then remedy.

And by writing something down and then stripping away the unnecessary complexity inevitable in a first draft, it exposes to me just what it was that my uneducated former self needed to grasp in the first place on the road to understanding. I think it's a skill that good teachers acquire to grasp what are the key "first steps" in understanding something to start someone moving along the road.
Click to expand...
It wasn't until I started teaching science (11 to 18) that I realised that I didn't really understand what I thought I did! That started a rethink on every topic that I then taught over several years.

Later when I moved into computers and gave technical presentations to industry professionals I made sure that I really did understand the subject and was often told that I was the first person they had met who could make a complex subject sound simple. I was even offered a job based on this ability. No I didn't take up the offer!

DV
 
TBH the topic I tend to feel is *really* widely misunderstood - even by 'experts' - is the behaviour known as coherence. The more I learned about it by working on instruments to use it, the stranger it became. In effect it is another face of QM but in 'classical' fields. It also confounds the widely asserted comment that the Michelson-Morely Xpt 'proved there was no Aether' - i.e. no Universal rest frame. It didn't! So this is another example of something often taught that is false.
 
chartz said:
Hi Jim,

I don’t question the use of shielded coax obviously.

I was wondering about possibly foo speaker and power cables.
Click to expand...

There can be an argument that because power amp output is unbalanced the leads may pick up RF which injects into the amp and bothers it. However a sensible amp design caters for this as one of the reasons for an output network, etc.

Similar comment wrt input power.
 
I love the classic experiments, unrelated, but none more than Faucault's pendulum or Kelvin's Thunderstorm
 
You must log in or register to reply here.


advertisement


Back
Top