methods i use as teaching aids to make my classes intersting
so lemme begin how i teach Back Emf in motors:
In electrical engg we cannot show current however we can show the effects of current, the stuff that you require is: some students, about 1 meter long insulated copper wire, two paper clips,magnet and a digital power supply(showing current and voltage)
to make the simplest motor in the world just make a few windings on a battery(AA size), about 20 of them wud be enough and then take out two ends on the either side of the wire... now scrap of the insulation from one side completely and half from the other side(otherwise it will not work), bend the paper clips so that they form a support to our motor, now put the entire apparatus on a bread board and give supply to the paper clip and make sure the magnet is in between the two paper clips.
Now block the motor and you will find a high current reading in the power supply as you leave the motor to rotate the current drops to almost to 40% of its initial value.. so something might have opposed the applied voltage thereby decreasing the potential difference and that is the BACK EMF which is the emf produced ny the rotating motor....i will you a link which is very helpful... do not get afraid with the american specification the local counter parts easily
[+] 1 user Likes dnvarun's post
Varun, its really good to know that you are passionate about teaching. At the engineering level, it is quite rare to see teachers who advocate experiment based learning. The labs are only used for scoring marks (that too by cooking up data). looks like really cool site.
dear lije,
there are many more sites which are quite interseting as well and what i think is that when i experiment i also learn a lot, it is pitiful state of technical education in our country that an engineering graduate doesn't even know how to solder. even i belong to that category, thats what i want to change
hello people,
i am back and today i am going to post how i teach the difference between paramagnetic, ferromagnetic and diamagnetic substances.
THings required:
1.ferrromagnetic material :one nail and one wrench
2.diamagnetic : your hand
3.paramagnetic a piece of aluminium
4.strong magnets

in your class you have to make sure you have three iron stools, one in our level and other two on top of each other, now stick the magnet on the stacked stools... and tie the nail on a piece of string and the other end of string to a nice weight( i use a vaseline container not empty of course).. adjust the height to the magnet suck a way that the nail floats in the air(i.e its attracted by the magnet but cannot go and attach beacuse of the string tied to the weight)
no while explaining diamagnetic bring your hand closer to the magnet and nothing will happen to the nail, then bring the aluminium sheets again nothing happens...
now if u bring the ferromagnetic material( iron wrench) it will sttarct thje mnagnetic lines of force towards it and the iron nail will fall, a beautiful simple and elegent demo but quite effective
Nice little demonstration, dnvarun.

I realize the importance and value of this approach, but education is such a vast discipline. Do you have a plan here? How are you going to be systematic about this? Or are you just interested in posting the stuff that you are trying out in your classes? In any case, this is a great idea and I wish you the best.

Finally, I would like to move this thread to the Parenting and Education forum. That would be a more appropriate place for it. I'll wait another day for your response before moving it.
"Fossil rabbits in the Precambrian"
~ J.B.S.Haldane, on being asked to falsify evolution.
Its cool with wherever i post it, i just want atleast on person to start thinking out of the box.. Technical education in almost all pvt institutions are beign taught ion the same way as it was 20 years ago... unless all of us move together it will be the same for the next 50 years also..

I have many plans this years for my lectures which would begin this JUNE ., and i will try more stuffs and the ones which work out i will post it.

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