## History Of Gravity

Gravity, one of the four main fundamental forces in nature. It is one of the most commonly observed forces in nature and yet it is as still one of the least understood of all forces.

Gravity was brought into fame by this famous apple shown above when it garnered enough strength and weight to detach itself from the tree and land on Newton’s head. This triggered his brain cells into thinking what made the apple fall down and thus Newton penned the theory of gravity.
The formula of gravity as given by him was:

And although he made the theory of gravity in a real short while it took him
twenty years to publish it in his book.Why? Because he had to prove that the mass of an object lies at it’s centre and for that he had to develop calculus to such a point that this could be proved. So in a way that apple was responsible not only for the discovery of the theory of gravity but also the the development in the field of calculus.
But why did newton have to prove that the mass lies at it’s centre?

Take a look at the above picture. Now if you see the formula you would see that given no action of any external forces the two bodies would attract each other with the force that is inversely proportional to the square of the distance between them. But what is the exact distance between them. Because mass can be distributed over a large volume. So if the two bodies touched each other the force of gravity is supposed to be infinite right? Because the surface has mass and the mass is at zero distance from each other. Well that’s what the mass being concentrated at it’s centre means. The force of gravity is taken by calculating  the distance between the centres of gravity of two continuous volumes of masses. That way no matter how close or how small or heavy the objects are they would never make the distance zero. Think about it!!

This theory was an absolute success as it was a unifying concept that not only explained the free fall of apples towards the earth but also the movement of the planets around the sun and the movement of galaxies and stars!

Of course the problem was that nobody including Newton actually understood what gravity was!They knew it was a force but the origin or the behaviour of this force still remains unknown.That’s when Einstein made his epoch making theory of special relativity and also the general theory of relativity.

Einstein made a simple observation. He already found that nothing can exceed the speed of light from all frames of reference via his theory of special relativity. Then he put up a thought experiment. He supposed that the sun would suddenly disappear. In that case the force of gravity keeping the earth in it’s orbit around the sun would just disappear too. But the light from the sun takes 8 minutes to reach the earth. So in that case we would still see the sun and yet we would not feel it’s gravity. That leads to the conclusion that the effect of gravity reached the earth faster than the speed of light! But nothing can travel faster than the speed of light. This apparent contradiction led him to modify the theory of gravity a bit. While there was nothing wrong with the magnitude of gravitational force it was the way the gravitational force lines acted that was changed.
Einstein said that gravity was the effect of bending the geometry of the space around it that led to the observation of a force acting.

Look at the above diagram. Suppose the the black line represents the path along which it is possible to move also called a dimension.
If we move both one will travel in a straight line while the other will travel in a bent line. If the lines become invisible it will seem as if the the object on the straight line is under no force but the object moving on the curved line is being pulled by a force that is changing it’s direction.

This is exactly what einstein called it. He said gravity bends space in such a way that it seems like a force.His theories were tested and proven multiple times and they were almost always found to be true. He was truly a remarkable genius since he explained  a fundamental force through geometry!

Now fast forward to the present we have new theories called standard model, string theory etc. However they still find explaining gravity a mystery! Yes what is gravity has been found but what explains it’s origin is still a mystery! While the world might be rejoicing at finding the higgs boson the boson does not explain gravity. And though string theory does predict it , the theory itself is yet to be verified by the scientific community.

Of course nowadays newer more expensive equipment are being created which sought to find the elusive particle of gravity called gravitons. And hopefully we will fully gain an in-depth understanding of gravity one day. Maybe one day the unknown apple shall fall on someone’s head again and we shall be saved from the ignorance of that special force called gravity!

## Solar Energy And The Optimistic Approach

So we have been talking about all the various problems of solar energy. And I am sorry to start it off with such a negative note but I did it because I wanted to end it on a positive note.
Yes , that’s right, solar energy holds a lot of potential And it “IS DEFINITELY” the future of our energy needs.

So why is everyone so optimistic on solar energy?
It’s simple. Because ever since life began on earth nature has always depended on solar energy for it’s continuous energy needs and evolution. Even the fossil fuels we use are indirect products of solar energy. The solar energy provided the animals and plants with energy as we know by photosynthesis and the food chain. These plants and animals died and their remains were buried under pressure and heat to form coal and petroleum as we know today.

So it’s obvious that solar energy should be our natural choice to be looking for. In fact Thomas Edison said that solar energy was the most natural as well as the most abundant source of energy available for us. Hence it is imperative that we try to find ways to harness it as much as possible.
So what’s the solution?
Simple!
Never give up!

That’s right scientists are striving today to make solar energy as much viable as possible and I have good news for you!!! Solar energy has made quantum leaps and it is proving to be a boon for many cities with abundant sunlight. Even during the night!

Here are some of the problems which are being tackled about solar energy.

Efficiency
The biggest drawback to efficiency is costs . Well scientists have been working on just those lines and they really have managed to increases efficiency and reduce costs as well. Yes they have developed new techniques and methods to greatly enhance consumer level use. It won’t be long before you will see everyone changing their power supplies just like how everyone is going digital from cable TV.

How?

1) Quantum dots
The solar PV cells are made even more tiny so that a greater surface area is exposed to the solar radiation resulting in good efficiencies.Nanotechnology holds huge promise in energy harnessing storage, as well as other industrial needs and the energy companies are no exception. And the best part is there has been steady progress in using quantum dot PV cells.

2) Splitting the solar spectrum
Solar PV cells use only a part of the solar spectrum to produce usable energy. The remaining part is lost as heat. This heat can actually reduce the efficiency of the system. Now given how summers can be blazing hot in India especially. We wouldn’t want a power supply that runs on solar power and yet gets fried with excess heat.

Now this is where material scientists(the broader group under which falls the nanotechnology scientists) play their part in making the cells more heat resistant and usable under heat. A new technology uses a material such that it emits only those wavelengths which are harnessed by the cells to produce energy.

Some people have even used the simple fibre optics which was originally used in communications. But since it characterises no loss transmission it is also a pioneer in using correct frequencies.

3)Concentration cells
Concentration cells uses parabolic reflectors to focus the sunlight onto a small area of the PV cells which is found to increase efficiencies amazingly. Photoelectric emissions which requires greater frequency to produce electrons of good kinetic energy, while  photoelectricity requires greater intensity of sunlight to produce more electricity.

Hence we have a reduction in costs with materials used and we get more usable energy from the same amount of solar radiation. So it’s a pretty neat technique.

But what about the production of energy during the night and what about cloudy and rainy seasons?
Again I have good news as researchers have found more and more efficient ways to store solar energy during the night time as well. A new method that they have developed is using lots of reflectors to focus the radiation onto a tower. That tower contains a form of salt and the solar heat melts that salt to a molten state. This molten state dissipates heat very slowly and it is kept in as much thermal insulation as possible. During the night the heat from this molten salt is used to power up homes during the night!! In fact it can well last for 8 to 10 hours for commercial needs of a locality. Not bad for a salt based system!

As for the seasonal changes that’s where the limitations come in. But researchers are still working on high altitude solar panels and increased efficiency panels. In fact here again fibre optics plays an optimistic role in transferring energy from high altitudes. However it won’t be enough for commercial energy needs and this is where the other renewable sources come to play like hydel energy, wind energy.

In fact if you think about it carefully summer is the time when there is no wind or rain and solar panels would rule. But the other seasons are sufficiently more windy and rainy which means that wind and hydel power would be a boost. So the various renewable energy sources complement each other.

After reading about so many new revolutionary inventions and techniques the world doesn’t seem so bleak due to the global warming catastrophe anymore does it? However that does not give us reason to continue our wasteful ways. We must continue working on sustainable development so that our future generations continue to reap the benefits of nature and keep the human race moving forward.

## Solar Energy

I am sure solar energy requires no introduction. Today India is being rocked by issues like the Nuclear proliferation treaty, coal scam etc. These are primarily because of the impending energy crisis that the world will come face to face with soon enough. And India is going to be one of the worst affected as it is one of the most densely populated countries. We recently got a glimpse of what might happen when fossil fuels get exhausted when there was a massive grid failure in the northern parts of the country. It was because of the fact that some of the states drew more than excess power that caused the generators to slow down thus disrupting the entire grid. It exposed the country’s dependence on fossil fuels only and the impending need to promote renewable energy sources. Sadly our policy makers are not too concerned with tapping alternative energy sources while all efforts to do so(nuclear power) is met with opposition for petty politics.
However there are plenty of other sources as well. While hydel power is a prospective source of energy in India it is consequential because it can damage fragile ecosystems and displace entire populations. Then naturally Solar energy seems to be the logical choice.
So what’s stopping them from adopting solar energy?
Two things:
a) Cost
b) Erratic supply
a) Cost
Yes like any other new product in the market costs determine how effectively it can be implemented. The biggest problem with solar energy is that it is very expensive. Yes it takes about 2000\$ just to install solar Photovoltaic(PV) modules plus even in the well developed sunny states of the U.S. the cost of solar cells is about 0.11\$ / kWh. Now that really is expensive if you compare it in the Indian currency.
b) Erratic supply
Yes it is true that India has a huge amount of solar radiation input being in the tropics and everything working out to be fine India should be having more than enough energy to compensate for the energy needs of the country. BUT we should also try to remember that India is a place where the monsoons cover the Indian skies with clouds for a considerable part of the year too. This does deter the energy supply and this would have been a cause of great distress among the millions as energy demands are high and an uninterrupted supply is necessary in many parts of the country. Plus supply during the night time would be a huge problem as there is no effective way to store energy obtained during the day.
But what exactly is  a photovoltaic cell?
A photovoltaic cell uses photons from the sun’s energy spectrum and converts it into kinetic energy of electrons.

It has an antireflective coating at the top to remove any sort to prevent loss of solar energy by reflection. As can be seen from the diagram, The photons strike the electrons at the junction of the p type and n type semiconductors to create a voltage difference. This voltage causes a current to flow in the closed circuit.
If solar energy needs no investment other than maintenance to continue then why should the initial high cost be a problem?
Well the problem comes from the fact that efficiency of solar PV cells is very small. Typical energy efficiencies are about 8 to 10% today. In fact all the major corporations of the world are working on increasing efficiencies as you read this article.

As you can see the technology used increases efficiency a lot. But what is not mentioned here is that the cost of increasingly complex technology is quite high. Efficiency determines the fate of new technology as solar pv cells are no exception.
But that does not mean that solar energy does not hold promise. For it has been calculated that the amount of solar radiation the earth receives at the sea level is more than enough to supply 8 times the energy requirements of the World’s population.

## Career Prospects in the field of Statistics and Economics

What are career prospects in the field of Statistics and Economics?

Economics being a social science is considered to be very vital in analyzing the effects of production, sales including consumption of goods on the economy of the user or the common man. The concept of economics is applied in every field; be it an industry, agricultural sector, banking sector, labor sector the principles of economics has a dominant role to play. In fact many of the leading industries including banks engage the services of economists to advise the industry or the organization on many of the policy matters including those involving production and matters relating to financial propriety and a host of other relevant issues. Every government will engage the services of economists to advise the government on various issues concerning the government policies on price control, banking regulation and such other related matters.

Those who aspire to take up economics as a career have the option to take up diploma course in economics. However, from the career prospects the diploma course may not be much feasible. Therefore, it is advisable that they take either graduate or postgraduate course in economics. As already mentioned in economics there are several areas of specialization like for example agricultural economics, industrial economics etc. Therefore depending on the specialization the career can be preferred. Remember, your opinion as an economic adviser has great value in terms of forming the future policies of the organization. Therefore it is a very prestigious and equally a responsible position.

A statistician is the person who works out with the data available all around us and as one expert puts it he ‘churns out’ the result. With his innovative approach and scientific principles he draws conclusions to various issues and it forms the basis for your policy making and plan future course of action. Every organization and particularly industries and the government need statistical data to regulate their work and also take effective policy decisions. Similar to economics, the curriculum in statistics consists of diploma, bachelor as also post-graduate courses. However in order to have promising career, it is advisable to complete either the graduate or post-graduate course with specialization.

According to experts, similar to economists, the carrier as statistician is very much promising. Considering the impact of statistical analysis on the future policies of the organization the position of statistician is considered to be very much important and it is one of the highly regarded positions. Normally, statisticians are appointed as consultants. However, some of the organizations and particularly the government would appoint them on a permanent basis or at least on a contractual obligation for certain period of time. Agriculture, industry and banking sector need the assistance of statisticians on a regular basis. It is also said that some of the educational institutions also require statisticians on teaching assignment. Those who have aptitude for teaching can look for these positions.  In fact some of the experienced statisticians even establish their own consultancy services where they even coordinate with experienced economists so that the client would get both the services in one roof.

## Why roads at mountains are serpentine?

Why roads at mountains are serpentine?

This is to reduce the effort. It follows the principle of a screw which in turn is a modified form of inclined plane.

See the pic on left. Though we have to do a greater work (against friction) the average force or effort is less and the risk or danger of accident is less.

## CBSE 2012

CBSE (Central Board of Secondary Education) has started online counselling for students and parents for Board Exams.

The first phase of this pre-exam counselling will start from Wednesday Feb 1,2012 and will continue until April 16 2012, for those appearing for board examinations this year.

Toll Free Number 1800-180-3456 is allotted to talk with experts. Anyone can call between 8 a.m. to midnight from Feb 1 to April 16, 2012.

This year, approximately 67 experts, including principals, trained counsellors from CBSE affiliated government and private schools and few psychologists are participating in tele-counselling.

## Where is electricity stored after it is generated but before it is supplied? (Chat Transcript from FaceBook)

###### Where is electricity stored after it is generated but before it is supplied?
• Mahesh Sable Electrical power cannot be stored and,therefore,power plants must produce power as and when demanded.power stations r connected in parallel hence load is equally distributed,electric Power can be adjusted with help of step up or step down transformers.

• Mathew Abraham Transformer does not increase power

• Chitraja Rajan The demand for electricity varies randomly within a day itself…so there should be something which should be adjusted according to the demand.

• Vishnu Mohan G huge capacitors? i think i read somewhere like this.

• Hi All, the question is very smart, i think electricity stored before generation is stored in Water(DAM), Uranium Rods(Nuclear), HydroCarbons(Coal, GAS). Electricity can only store when it is in Direct Current format like in Batteries, Capacitor(its a very small time to store/release) Well there are many source where we can store electricity. When electricity is in demand then Power generation takes place within huge Alternators, this powers generation takes places in terms of Phase Shift between all the power Houses across the country, if this phase shift is disturb then power grid fails. after this the transformers come into picture so as to reduce Resistance loses.

•
• Kannan Kannan Ps in my little knowledge electricity unable to store continuing process of generater get current
>________________________________

• Chitraja Rajan at the generation side electricity is high ac current ..if it is converted into dc then there should be large containers to store them and also need suitable convertors to convert it in either form every time

• Mathew Abraham In modern generators, there are equipment to control the rate of flow of water and in turn rate of rotation as well as the power generated. SO, it is quite right to say that electricity is generated as and when required. When you switch on a device power generation also increases until it reaches maximum capacity. Thereafter we will get less power. Remember the low voltage we suffer during the evening when the power consumption is maximum a few seconds ago · Like

## What Type of questions are asked in Viva Voce?

The methodology of questioning varies from examiner to examiner. The normal way of questioning is to start from the experiment you are alloted.
Example:

What experiment are you doing?
Ans: To determine the value of unknown resistance using metre bridge (Don’t say just metre bridge or unknown resistance alone; you should tell the complete aim of the experiment.)

What is the principle on which the experiment is based?

Ans: The metre bridge experiment is based on the Wheatstone’s Bridge Principle

(You can go on to state the principle; or it will be the next question)

Then the examiner may go on to ask some tricky questions related to Wheatstone’s Bridge.

The questions are generally based on what you answer and usually different sections are asked when you do not give a satisfactory answer.

Have good presence of mind and think before you answer.

You can find some sample questions here arranged experimentwise

## A VERY INTERESTING CONVERSATION

A VERY INTERESTING CONVERSATION
An Atheist Professor of Philosophy was speaking to his Class on the Problem Science has
with GOD, the ALMIGHTY. He asked one of his New Christian Students to stand and . . .

Professor : You are Christian, aren’t you, son ?
Student : Yes, sir.
Professor : So, you Believe in GOD ?
Student : Absolutely, sir.
Professor : Is GOD Good ?
Student : Sure.
Professor : Is GOD ALL – POWERFUL ?
Student : Yes.
Professor : My Brother died of Cancer even though he Prayed to GOD to Heal him.
Most of us would attempt to help others who are ill.
But GOD didn’t. How is this GOD good then? Hmm?

(Student was silent ) Continue reading “A VERY INTERESTING CONVERSATION”