Wednesday, July 13, 2011

Skewed Definitions

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One blessing of our Village School Curriculum was that no one asked us to 'define' anything.

No doubt we were asked to 'state' Pythagoras Theorem, but that was easy and understandable.

But in the very first Physics Lecture I attended, nervously, in my College, I was dictated from the pulpit the 'definition' of Least Count of a Vernier Calipers.

What a horrible way to start learning Physics! Feynman's Lectures would be a disaster if he started like that. I am amazed that I could tunnel through the insurmountable repulsive barrier of College Physics and ended up drawing a decent pension, despite my inability to grasp definitions of things and thoughts.

Anyway, I mugged up unthinkingly: "Least Count is equal to (1 msd - 1 vsd)"; and got a rank.

But when I joined IIT KGP and entered the Optics Lab, I had to reverse my definition as "(1 vsd - 1 msd)"; for, there was this curious and thoroughly enjoyable spectrometer with a 'negative reading vernier'.

Then in our University, we had to define fringe width; and we did it gloriously as "the distance between one bright (or dark) fringe and the next. Equivalently, it is the width of a bright or dark fringe".

That was ok, because all the experiments in our lab were '2-beam interference' things like: Double slit, Biprism, Lloyd's Mirror, Newton's Rings...

But when I had to teach Physical Optics (my favorite to this day), there was this Fabry-Perot Interferometer; and i think it was Hecht and Zazac (what a lovely book!) that started talking about a horrible thing called: FWHM.

And that expanded as: "Full Width at Half Maximum".

A mouthful!

And then there was the definition of this CRP (Chromatic Resolving Power) on which I still have something to publish (too late now). I talked about it in one of my blogs.

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All this unhelpful reminiscence came up because here is a cute news item in today's DC titled:

"AP team redefines hydrogen bonding"

Excerpts:

DC: "The new definition of hydrogen bonding will help in developing new drugs for several diseases and better understanding of the chemistry that makes things like water and DNA so unique in nature and property".

gps: Chemistry looks like a delightfully fruitful subject; apparently lives can be saved by suitably redefining 'bondings'; Hydrogen or Carbon.

DC: "Hydrogen bonding is not string theory or gravitons, which no one has ever seen yet"

gps: What you see depends on what glasses you wear. For example, Lord Krishna equipped Arjun in the battle field with 32-dimensional lenses and lo and behold...Arjun started seeing ghastly things; and was so frightened at what he saw that he begged Lord Krishna to take his perfidious glasses away...

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3 comments:

Dharmesh Jain said...

How is it 'too late' to publish something? (Given that it hasn't been published already.) ...Or how about 'publishing' on the blog itself, removing all the middle-men!

G P Sastry (gps1943@yahoo.com) said...

Let me tell you something beautiful about old age:

Things that seemed frightfully important, urgent and pressing once seem ridiculous in old age...and you wonder how you could really be such a simpleton all those decades.

As Hamlet said:

"Ripeness is all"

There are now so many more things to do and enjoy before it is too late that all your old passions and flames look childish.

Pratik said...

If one starts the main scale with 1 instead of 0, the definition,
LC=1 msd-1 vsd, would work fine as it carries a minus sign with it for a negative Vernier. So when you add it to the main scale reading it is automatically subtracted.

A common problem now is that many students know the definition as LC=1 msd/no. of div on vs, which
only works for n msd=(n+1) vsd.