I was triking along Princes Street going from The Mound to Queensferry Street and I was right underneath the overhead power lines. I was interested to notice that the cycle computer on the trike had stopped reading the speed and was saying I was doing 0 mph. Now I had a thought that if the power lines had a strong magnetic field, they might interfere with the communication between the magnetic sensor on the wheel and the receiver on the handlebar. I later had another similar experience whilst riding alongside a tram on Shandwick Place (I wasn't underneath the power lines this time). It certainly is thought-provoking; if the trams can affect my magnetic sensor, what are they doing to me?
CityCyclingEdinburgh Forum » General Edinburgh
Trams and their magnetic field
(17 posts)-
Posted 11 years ago #
-
I hope that they're pacemaker-safe
Posted 11 years ago # -
I suppose they must have checked this out before introducing the trams? But a good thought, though ..
Posted 11 years ago # -
Doesn't part of the trams braking system use magnets to effectively "sook" it down onto the track?
Amir, was it not you who had your wireless speedo interrupted by a pulsing LED light?
Posted 11 years ago # -
I had one wireless Speedo that was affected by a B & M non flashing light. It also went hairwire at the start of a sportive due to the timing mat.
Posted 11 years ago # -
I've noticed my cheap Geonaute Ant+ speed sensor can give some odd readings near trams. It seems to sense too often that was causing my gps auto calibration to set the speed to about 4km/h max when I started from work next to the tram lines.
The other strange thing we've noticed at work which seems to be since the tram electrification went live was the mains voltage rises to about 258V at night (well above the 253V maximum) and causes UPS problems. It may be unrelated but its odd all the same.
I may well have to take a compass into my desk and watch what happens when a tram goes by
Posted 11 years ago # -
I may well have to take a compass into my desk and watch what happens when a tram goes by
Good idea! I wonder where mine is...
Posted 11 years ago # -
My compass is always in m camera bag.
My wireless speedometer occasionally acquires up to a third of a mile whilst in the pocket of my shorts locked in my locker during office hours.
Posted 11 years ago # -
This thread has finally given me a viable analogy for photons and ionisation and I have been searching for one for over a decade.
Thanks, therefore to Alanr.
I like to think of myself as having at least a scrap of creativity, so I offer the fact it's taken ages to think of a macroscopic world analogy as evidence for quantum mechanics being really, really weird.
There's three instances of electromagnetic radiation you need to worry about:
1) When it can ionise the atoms in your body, which means it's given so much energy to an electron in that atom that it grows up and flees the roost; leaves the atom to pursue another career; just needs some space(it's not you, it's me) etc etc. This isn't in itself a bad thing - it happens in just about every chemical reaction and if it didn't, you'd be dead before you knew it. Buuuut, in the specific case of the atoms in your DNA and RNA, you don't want them ionising at random, because that would make the ionised 'letter' of DNA/RNA go shonky, and if that bit is the latter half of the code which every cell has that tells it to replicate once then die, you've got cancer.
b) When you are an electronic device that utilises that frequency of EMR(electromagnetic radiation). Since you are an electronic device and therefore extremely stupid, you won't be able to tell the difference between the noise and the signal, and you'll start getting things wrong very soon.
Third) When there's so much of it that it heats you up by sheer dumb force of wattage and you go on fire. It doesn't really matter what kind of EMR it is, you just put enough of it out there and stuff goes on fire.
Now, Instance b very much applies to a wireless speedometer. They are looking for a very tiny signal from the sensor, so it only takes an even tinier signal to confuse it.
Instance Third plainly can't be happening because we'd all be on fire by now.
So what about Instance 1? Well, the kind of emission that screws up a wireless speedo is long wave radio, because that's what they're looking for. Long wave radio photons are puny and cannot knock electrons off their atom, which finally brings me to my analogy because the intuitive thing to think is: sure, one LW photon can't do it, but surely a squad of them working together can?
No. It's isn't like a human-sized world physical task where one very strong person can do it, but several normal people could team up and do it too. I've tried to think of analogies that don't allow this kind of teamwork and failed for over ten years, until today.
My analogy is: trying to get into an age-restricted film. If you turn up, aged 10, to watch an 18, you'll be refused. If you turn up with a friend from your class, you'll still be refused, even though you can correctly argue that your combined age is 20. If you turn up with a million ten-year olds, not one of you will get to see the film.
Thus, no amount of LW radio waves will ever present a cancer risk. Same goes for the microwaves emitted by mobile phones. Ain't gonna happen any more than six eleven year olds turning up at the Post Office and collecting a pension.
In other news, I farted just now after eating chilli and it's ghastly.
Posted 11 years ago # -
/* long sustained applause, developing into standing ovation */
For the analogy, not the fart.
Although the fart may well deserve it also.
Posted 11 years ago # -
"If you turn up with a million ten-year olds, not one of you will get to see the film."
That is, unfortunately, where your analogy might fall down, provided there are not one million ushers, projectionists, cinema managers and counter staff to ensure that all children are caught before they stampede into the auditorium. Otherwise, very well done.
Posted 11 years ago # -
"If you turn up with a million ten-year olds, not one of you will get to see the film."
monty python, life of brian, 1979
ok, i didn't get in, but it was close
very close
Posted 11 years ago # -
That is, unfortunately, where your analogy might fall down, provided there are not one million ushers, projectionists, cinema managers and counter staff to ensure that all children are caught before they stampede into the auditorium. Otherwise, very well done.
Newps, that is the dumb wattage situation, in which case you can't get cancer because people who have already died from being on fire have a 0% incidence of that.
Posted 11 years ago # -
But if the children merely overwhelm the staff, without setting fire to the cinema, one of them might make it as far as the auditorium: one of them might get to see the film. I am merely exploiting one of the ways in which children do not resemble low-energy EM quanta.
Posted 11 years ago # -
I feel there's a section of my donated parenting book missing...
SRD?!
Posted 11 years ago # -
It'd be good if children did have to occupy distinct non-continuous energy levels, being.promoted to the next every year or so. You could skip out the stroppiest stages or keep them on one size of clothes for more than a few months.
Posted 11 years ago # -
@uberuce
Well....I'll continue to protect myself from non-ionising ultraviolet radiation and let's not forget that the human body is a mechanism for receiving and transmitting information. Visible light for one has huge effects on us. I wouldn't go ruling out the possibility that lower energy radiation has an effect on the body just because it can't ionise anything. If we (or any of the many organisms that live in and on us) can detect it by any means then we may end up reacting to it.
@wingpig
I like your idea of childhood orbitals. Beware, however, generating an excited triplet state.
Posted 11 years ago #
Reply
You must log in to post.
posts
