## Tuesday, July 28, 2015

### TRIBUTE TO A P J ABDUL KALAM

BHARATA RATNA A.P.J.ABDUL KALAM

## Monday, July 27, 2015

### What is Science?

Though I am not an eligible person to define this term, I would like to share my understanding as follows:

Science is an organized study classified into various branches to bring out details to understand the entire world. The study involves observation, put forth hypothesis, performing experimentation, compilation and understanding of results, establishing the facts.

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"Science" description in words of famous scientists:

"If you are going to teach people to make observations, you should show that something wonderful can come from them. I learned then what science was about: it was patience. If you looked, and you watched, and you paid attention, you got a great reward from it — although possibly not every time".

"Science teaches the value of rational thought as well as the importance of freedom of thought; the positive results that come from doubting that the lessons are all true. "

---  Feynman

## Tuesday, July 7, 2015

### What are Eddy Currents?

Eddy currents are currents induced in conductors when exposed to a changing magnetic field due to relative motion of the field source and conductor; or due to variations of the field with time. This can cause a circulating flow of electrons within the body of the conductor. These circulating eddies of current have inductance and thus induce magnetic fields. These fields can cause repulsive, attractive,propulsion and drag effects. The stronger the applied magnetic field, or the greater the electrical conductivity of the conductor, or the faster the field changes, then greater the currents that are developed and the greater the fields produced.

Eddy currents, like all electric currents, generate heat as well as electromagnetic forces. The heat can
be harnessed for induction heating. The electromagnetic forces can be used for levitation, creating movement, or to give a strong braking effect.

Eddy currents can also have undesirable effects, for instance power loss in transformers.

### What is short circuit?

A short circuit is simply a low resistance connection between the two conductors supplying electrical power to any circuit. This results in excessive current flow in the power source through the 'short,' and may even cause the power source to be destroyed. If a fuse is in the supply circuit, it will do its job and blow out, opening the circuit and stopping the current flow.

Short circuits can produce very high temperatures due to the high power dissipation in the circuit.

### What causes different colors in flames?

In the flame, electrons get excited and pushed to higher energy levels by the heat energy. When they fall back down, they give off photons of light of different colors, based upon how far they fall. Different temperatures cause electrons to jump to different levels, but different types of atoms also have energy levels that are different distances apart. Thus putting copper into a flame causes a green glow because electrons on the copper atoms are falling and jumping exactly the right distance to emit or absorb photons of the frequency we see as green

### Air Composition at Sea Level

NameSymbolPercent by Volume
Nitrogen N2 78.084 %
OxygenO220.9476 %
ArgonAr0.934 %
Carbon DioxideCO20.0314 %
NeonNe0.001818 %
MethaneCH40.0002 %
HeliumHe0.000524 %
KryptonKr0.000114 %
HydrogenH20.00005 %
XenonXe0.0000087 %

### MECHANISM OF CURRENT GENERATION IN GAS FILLED IONIZATION CHAMBERS

courtesy: Spring 2010 Radiation Detection & Measurements