The Tim: Notice I wasn’t just talking about arguing with your teacher in class - I agree, that’ll just get his or her back up and may cost you.
I’m talking about going the extra mile to come up with an experiment to prove the teacher wrong. Do it as an extra assignment, or just on personal initiative. If the teacher degrades a student’s mark for taking the trouble to learn more (as opposed to just arguing or saying, “My dad says you’re wrong”), then he’d be sticking his neck out a mile.
Sam I noticed that and agree it would be a good learning experience. In some places however it would still be risky without a good way to brow beat the administration into doing something.
With the co-operation of my duck, “Arnold,” I recorded his quack.
Here it is. (WAV file)
Then I put Arnold in an echo chamber.
Sure sounds like an echo to me. Wanna see me do it again?
I’m sorry, but i just had to revive this old thread to bring this to light.
http://edition.cnn.com/2003/TECH/science/09/08/duck.quack/index.html
Its from CNN
Thanks for the news link, Ottoerotic. Apparently Trevor Cox hadn’t listened to my sound files. 
The only thing more ridiculous than a scientist doing a test like this in the first place is the excuse they give for the source of the urban legend:
Or someone dreamed it up, and gullible people, with no knowledge of acoustics or physics, bought it and repeated it endlessly without thinking. At least that’s my theory.
I don’t know the physics teacher in question, but I love it when my students prove me wrong, as long as they do it correctly and politely. It shows that they’re thinking, that they care at least a little about the subject, and that they aren’t afraid to question the voice of authority when it doesn’t sound right.
When a student proves me wrong about something, I’m much more likely to give bonus points than to damage their grade.
How can a teacher injure your academic career? By not teaching you something that they teach to the rest of the class? I can’t understand this!
A teacher can injure your academic career by giving you bad grades. In this case, undeserved bad grades.
On the other hand: I’ve heard tell of teachers who will tell their students something that is obviously, clearly, and patently wrong, as a deliberate test. Any student who regurgitates that “fact” clearly didn’t think about it, and gets docked points as a result.
My advice would be to dispute the teacher whenever he or she is wrong. Don’t do it during class (that can be viewed by the teacher as an attack, and at best uses up class time that could be spent on other matters), but ask if you can see the teacher outside of class some time, to clear up some questions you have. Then, if the teacher tries to punish you for questioning authority, take it up with the administration of the school. And if the administration doesn’t back you up, then transfer to a different school. If the school isn’t trying to get students to learn, then there are worse problems there than an ignorant teacher.
Well, they can give you an undeserved bad grade, which could reduce your chances of getting into the college of your dreams.
Which makes them pretty bad teachers too, albeit in a different way. Tricks are for magicians, not schoolteachers.
No, I still don’t get it. What have your marks in class got to do with getting into University? That will surely depend on passing your externally moderated exams?
Some universities also use your high school GPA to determine who gets in.
My brother loves to argue with his instructers at the local CC. He will spend an hour after class talking with them, and if he can’t prove to them he is right he will do a report, and show them. He dosen’t just say “you are wrong, because I say so” he will explain why he thinks he is right. He was offered a possition to teach out there because of his knowledge, but turned them down. He isn’t big on public speaking.
Things my physics teachers told me in high school:
electrical wires are multistranded because electricity travels only on the surface of the wire and the more strands, the more surface area.
if you turn on a light in a dark room, if you observe carefully you can see that the light reaches the corner of the room slightly after areas of the room nearer the light.
Sam Stone, bro 2 needs to think very carefully whether the teacher in question is a scientist with a love of learning or a power monger in love with their own authoritativeness.
Teachers come in both kinds, and the latter kind can turn very very nasty when proved wrong or questioned, no matter how politely or indirectly. As someone who was precocious brat of a teenager I speak from experience…
Kids really need to learn that teachers are not mystical, infallible holders of all knowedge. They screw things up and get things a**-backwards, just like the rest of us.
quote:
I find this an odd idea. Surely asking your school is like asking your mother for a reference - most of the time it will be marvellous, occasionally it might be accurate, but you won’t be able to trust it at all.
OKay, Princhester confused me with his statement that in high school he was told:
This was said in the context that such a thing was false.
So are you saying that electricty doesn’t flow on the surface of the wire, or that you don’t get more surface area with more strands? The second assertion seems to not be the case as I run it through some basic mental geometry, so I presume that you are saying that electricty doesn’t flow on the surface of the wire.
If so, I need a quick lesson on this. What little I could find on Google seems to indicate it does. Please enlighten me…
Wires that are multi stranded are that way only to make them more flexible. No other reason. Electricity travels through the metal.
This was said in the context that such a thing was false.
So are you saying that electricty doesn’t flow on the surface of the wire, or that you don’t get more surface area with more strands? The second assertion seems to not be the case as I run it through some basic mental geometry, so I presume that you are saying that electricty doesn’t flow on the surface of the wire.
If so, I need a quick lesson on this. What little I could find on Google seems to indicate it does. Please enlighten me…
…
I think I can see confusion developing here, and confusion may also explain the original problem Princhester had with his teacher. The following points may be of interest:
A typical electric current flowing in a wire - say, a wire in a hand-held torch - passes through the full cross-section of the wire.
A static electricity charge - say, on the dome of a Van de Graff generator, stays on the surface of the conductor.
A high frequency current exhibits a ‘skin effect’, that is, the intensity of the flowing current falls off the deeper you go into the conductor. See
http://www.epanorama.net/documents/wiring/wire_resistance.html
Things my physics teachers told me in high school:
electrical wires are multistranded because electricity travels only on the surface of the wire and the more strands, the more surface area.
if you turn on a light in a dark room, if you observe carefully you can see that the light reaches the corner of the room slightly after areas of the room nearer the light.
…
Well, we covered multi-strand wire earlier - the skin effect is quite pronounced by 1 Mhz and above. A good example of the need for multi-strand here is loudspeaker wire. If you have a DC current, of course, the only reason for multi-strand is flexibility and resistance to cracking.
A light in a dark room - well, taking light to move at about a billion (American) feet per second, and assuming the corner of a room is 10 feet further away from the light bulb than the centre, we estimate that light gets into the corner 1/100,000,000 of a second after the middle is illuminated.
I don’t think an unaided eye could notice this, but modern measuring equipment certainly could. So perhaps he meant that you were to observe carefully with some specialist kit?
Alternatively, he got 1 out of 2?
Got it. Thanks.