Archive for November, 2008

Thirukkural – 377

November 11, 2008

வகுத்தான் வகுத்த வகையல்லால்

கோடி தொகுத்தார்க்கும் துய்த்தல் அரிது.

VahutthAn vahuttha vahai allAl kOdi

ThohutthArkum Thuythal arithu.

 

VahutthAn – The Devisor or the designer

Vahuttha Vahai allAl – away from the ways and means decreed

kOdi ThohutthArkum – Even for those who have earned millions

Thuytthal – to consume and enjoy

Arithu – is next to impossible

 

Here the poet talks of three activities of economics. Thohutthal – collection, Vahutthal – Distribution, Thuytthal – Consumption. One may earn and accumulate wealth. He may even plan and distribute the wealth in his own way. But what he can on his own consume and enjoy, is already decreed by God. Nothing more and nothing less. We may compare this with the present day saying: “Dane dane par likha hai, Khanewalleh ka naam” – (i.e.), in each grain is engraved its eater’s name.

 

Even a person who has earned millions cannot enjoy his wealth any more or any less, except by the way decreed by the Eternal Designer.

 

 

 

 

FAQ on Electrical Power

November 6, 2008

 

What is Power?

Power is the capacity to do any work. For the same work, a less powerful man will take more time and a more powerful man will take less time. Power is the rate at which work is done.

 

What is work?

A body remains at rest unless it is moved by a force. The distance the body moves is a measure of work done. The amount of force required to move the body and to keep it moving depends on forces that resist movement, like friction. More friction means more work need to be done to move the body by the same distance. This may require higher force. Hence force multiplied by the distance gives a full measure of the work done. How quickly the body can be moved by a distance depends on how much force is exerted and for how long. If the force is just enough to overcome the friction, it will barely move. If the force is increased it will move faster. With the higher force the work is done faster. The capacity to exert this higher force over a period of time is known as power. Power is measured as the rate of work done.

 

What is electrical power?

Electrical power is rarely used directly as electrical power. It is always converted to: mechanical power in pumps and drills, heat power in furnaces and heaters and light power in lamps etc. Efficiency of conversion varies as per the devices. Raw electrical work is done by charges moving in an electrical field created by voltage (Electro Motive Force). The medium, like an electrical conductor, resists the movement of charges. This property of electrical conductivity is known as resistance. The amounts of charges that move overcoming this resistance represent the raw electrical work done. More voltage, more charges and more work. Hence voltage multiplied by amount of charges moving gives us total electrical work done. The electrical power is the rate of this work. Rate of movement of charges is known as electrical current. Now it is easy to see that raw electrical power is just voltage multiplied by current.

  

Ohm’s Law

In general, when Voltage(V) increases the Current(I) increases. For a particular conducting material, (eg) aluminum, I, the current is proportional to applied voltage, V.

                      i.e. V = kI.

This constant k is known as resistance (R), measured in ohms in the name of the scientist who found this law,

           Ohm’s law, V= I R.

Now we can express electrical power, P as,

            P =     VI     =      I2 R    =      V2/R      measured in Watts.

 

What is Direct Current and Alternate Current Electricity?

All naturally available forms of electricity are direct current.

(eg-1) Static electricity obtained by charging up certain materials. When an ebony rod is wiped vigorously by a silk cloth, the ebony rod gets charged up to a voltage. When touched to earth it discharges by passing a current to earth.

(eg-2) When a lightning strikes, a highly charged lower cloud arcs through to a high point on the earth, discharging a heavy current with a flash of arc.

Other man-made devices, like thermo-couples and batteries also provide an easy source of direct current. About Alternate Current Electricity we will see later.

 

What is a Generator?

For heavier applications we needed a more powerful source of electricity. Movement of an electrical conductor in a magnetic field was found to produce an electrical current in the conductor. This phenomena lead to the discovery of a device known as a dynamo. When a conducting coil of a dynamo was rotating between the poles of magnets, it was initially found to produce a current in alternating directions as they pass through north and south poles of the magnet. But it was converted to direct current by a device called split ring. This, in contact with metal brushes, eventually reversed the circuit for every half rotation of the coil mounted on the shaft, thus producing the unidirectional ‘direct current’. These dynamos were the earliest electricity generators, used in place of batteries, for heavier applications such as arc lamps and heaters.

 

What is a motor?

In a generator, ‘movement’ in a ‘magnetic field’ produced ‘electricity’. In a motor electricity’ in a ‘magnetic field’ produced ‘movement’. When a current was injected into a coil mounted between the poles of a magnet, the coil along with the shaft was found to rotate. The device, known as a DC motor, found major applications in traction and drives in factories, textile mills and transportation. More and more powerful DC generators were manufactured and DC grids were formed to supply different customers. Thomas Alva Edison was the great engineer who pioneered such grids, starting with New York City, way back in 1880. (Reference quoted).

 

Then, why we did not continue with DC?

When we started, we talked about ‘power’ and ‘work’. No matter how powerful you are, you exert less force for a smaller work and more force for a heavier work. Same is the case with electric power. We need lower voltage for smaller devices like bulbs and heaters, whereas we need higher voltage for electric traction and arc furnaces etc. Further for transmitting power from a generating station to a consumer substation, it would be preferable to use a much higher voltage. This will result in lower currents and higher efficiency of transmission. The DC electricity once generated at a specific voltage is not suitable for ‘transforming’ into another usable voltage.

 

What about AC?

One man, Nikola Tesla of Hungary, wondered why at all the naturally produced alternating current in a dynamo should be converted to DC?  He invented AC motors which could run on alternating current. In the process he faced a major problem of stalling of the motor. Hence it was not easy to promote the use of AC systems, though improved designs of AC generators were developed.

The famous technocrat, George Westinghouse of USA was not interested initially so much in electricity. He found no future in electricity business, unless one finds a way of transporting electricity through a large distance. But, he happened to see a piece of report about a device developed in Europe to transform AC voltages from one value to another. This gave him a spark of an idea to harness AC power for generating, transporting and utilizing at different user levels. This idea changed his entire career.  He bought up this device known as transformer, and made suitable design changes. In March 1886 Westinghouse Electric Company commissioned the first AC grid, in Massachusetts, USA. This led to several AC grids to be commissioned in USA.

 

 

What is 3-Phase and Single Phase AC?

The war against Edison’s DC grid was still on, not won. AC cannot win unless reliable AC motors were developed to power the drives of the factories and transports.

Mr. Tesla was delighted at the success of AC grid and promised Westinghouse he will give him the AC motors he needed. They entered into a pact to develop the AC motors. Mr. Tesla dealt a master stroke when he reversed the roles of stator and rotor of the motor. The magnets in the rotor were made to follow the alternating magnetic field generated by the current coils on the stator. Immediately he found the solution for stalling. What is required is only to find a way to produce a rotating magnetic field. The induced magnetism in the rotor will automatically try to follow the rotating magnetic field in the stator and in the process will try to rotate as fast as the rotating magnetic field. One sure way Tesla found, for creating the rotating magnetic field, was to think of a poly-phase AC windings which are out of phase with each other in a way to complement one another, (very much like pistons in the cylinders of the car). This finally led to AC induction motors and 3-phase AC generators. This made a large electrical network possible through devices called transformers. High voltage was used for long distance transmission of electricity and gradually lowering the voltages to lower levels for smaller networks and then to domestic level of 230V or 110V.  It is like carrying Rs 100,000, (a) as 100 nos. of Rs.1000 notes while traveling, and changing them to (b) 1000 No. of Rs 100 notes at the time of spending. Finally we have the 3Ph AC grids as existing now everywhere. For a normal domestic use one phase of this 3-Phase AC is used. All such single phase loads are distributed equitably among all the three phases to obtain a balanced 3-phase load.

(Reference quoted).

      

In the AC system when the current is alternating either way, how at all the power gets transferred to the device?

When you consider alternating currents, the input voltage is alternating between a positive and a negative voltage, as a sine wave, (normally) at a frequency of 50 or 60 cycles per second. Coming back to our discussion on electrical power, V*I is still the power, but in this case, it is an alternating power, or is it? Let us consider an AC circuit with a resistive load such a heater. As before I2R is the power consumed in the circuit. Though the current is alternating, it will still heat up the coil either way. The power also will continue to be transferred from AC power source to the heater, irrespective of alternating current. So the average power in the circuit will be R multiplied by the average of I2 over a cycle of the alternating current. This average of I2 over a cycle is knows as the Mean Square value. The square root of this current is known as the Root Mean Square current or IRMS. Same way, we can define a VRMS for the voltage wave form. Without going into rigours of mathematics, Power in a AC circuit with a resistive load, can still be expressed as:

 

           P =   VI    =    I2 R   =    V2/R      measured in Watts.

 

But however herein, V and I are RMS values of Voltage and Current.

For a pure sinusoidal waveform, RMS value = Peak Value/ √2

In an AC electrical system, when we refer to magnitudes of voltage and current, we normally refer only to there RMS values.

 

What is energy?

Work done over a period of time consumes energy of the source. A man spends his energy when he executes a manual work. When he is exhausted (of his energy) he is not able to work any more. Similarly when we use electricity we consume electrical energy and convert them to useful work in devices like heaters, motors etc. Electrical energy is measured as:

            Power x Time or         Voltage x current x time

Voltage is measured in Volts and Kilo Volts

Current is measured in Amps and milliamps

Power is measured in Volt-Amperes or Watts or Kilowatts

Energy is measured in Watt-hours or Units (Kilo Watt-Hours)

 

Reference:

THE GRID, by Phillip F. Schewe, Joseph Henry Press, Washington, D.C. (2007)

 

 

A precise solution to the current Sri Lanka – Tamil problem

November 3, 2008

 

I am giving below the recent discussion I had with Mr. Rajiv on the Srilankan war on Tamil insurgents. Apart from the subject matter, the tone and the open minded manner in which the discussion proceeded are just exemplary. I wish to share the same with my readers. 

 

darashikoh Says:

From : http://rajivsramblings.wordpress.com/2008/10/25/

Today’s Hindu editorial has ably enunciated what the precise solution is – in terms of India’s response to the Sri Lankan problem.  Before I elaborate on this: out here in Chennai – I can see a lot of literature which has suddenly exploded ………which supports the LTTE cause.  It is more like the local government is hand in glove with this whole thing.  It is difficult to believe that if the government does not support LTTE as a banned organisation ………….then such literature proliferating so liberally ………is very scary indeed. 

It is more so evident in the small time newspaper stalls.  Although I cannot really read the Tamil headlines ……….the pictures depict a more sympathetic picture of this gruesome organisation. 

I’m just wondering why the local Congress party has not got its reaction together.  Yesterday there was an incidence of vandalism to the statue of Rajiv Gandhi – and a few local congress supporters were protesting about it today.  Beyond that the party needs to get its act together to counter the political wave in favour of the LTTE.  It is only the AIADMK which has taken a strong and firm stand on this issue.  For one thing – those LTTE sympathisers strongly think that Rajiv Gandhi’s assassination was justified and that he deserved it.  This kind of thinking is appalling – and goes against the overall thinking across the country that the assassination was wrong and that the LTTE should be punished for it.  

Now coming to the solution which was laid out in today’s Hindu editorial goes as below:

In the first place, no comfort should be given to the LTTE, which is a terrorist organisation banned in 30 countries, including India.

Secondly the Indian commitment must be to finding a solution that envisages devolution of powers to the Tamil regions within a united Sri Lanka, which would mean giving no quarter to the demand for an independent Eelam.

Thirdly, mainstream political parties in Tamil Nadu need to make a sharp disctinction between the current military plight of the LTTE and the displacement and suffering caused by the conflict, affecting an estimated 230,000 Sri Lankan Tamils.

The right response for Government of India and the people of Tamil Nadu would be to offer food, clothing, medicines, fuel and other essential goods as well as other logistical facilities required to reach them to the people through the Sri Lankan government whose President Mahinda Rajapakse has declared his commitment to bring their hardship to an end “in a short time.”

 

 

Nagarajan Says:
October 27, 2008 at 12:18 am

 

In a feedback to Times of India news item, I had sent the following comments. It was kindly published by them. Your may also may find this interesting.

 

L V Nagarajan, Mumbai, says: “I read the story and all the comments. I have following questions which need answers: 1. LTTE is declared as a terrorist organisation. In the last 10 years, what are the terrorist activities in which LTTE is involved, especially outside Sri Lanka? 2. Our beloved young prime-minister Rajiv Gandhi was assassinated by an LTTE sympathiser, possibly as a plot by LTTE. How many lacs of Srilankan Tamils should die as a revenge for this grave crime by LTTE? 3. When Sonia Gandhi and Priyanka can consider pardoning Nalini who was directly involved in Rajiv Gandhi’s assassination, why the Indian government can’t pardon unconnected Srilankan Tamil people and help them in a humanitarian way. Or, was Sonia’s pardon only a political gimmick? 4. Indian Government has intervened many times in the past, in Tamil struggle in Srilanka. Almost all the time the effort was against Tamil interests, (except during a brief period in Indira Gandhi’s time.) Why should they fight shy of intervening now? Is it in respect to the memory of Sri Rajiv Gandhi? 5. Srilankan Tamils are of Indian origin. Have not the government of India acted more sympathetically towards other people of indian origin struggling in other countries? 6. When some body raises these questions why should they be considered as sympathisers of LTTE? (I am Not a sympathiser of LTTE). Is it because, as of now Srilankan people’s only saviour is LTTE? I do not know. I only hope the innocent Tamil people of Srilanka find an early solution to their struggle. God save them.”
[24
Oct, 2008 0208hrs IST]

I really would like to know your answers for the above questions, so that I can correct myself if I am wrong.

 

darashikoh Says:

October 28, 2008 at 12:37 pm

Nagarajan,
Here is my response to your questions:
Question:
How many lacs of Srilankan Tamils should die as a revenge for this grave crime by LTTE?

Answer:
You are connecting the assassination of Rajiv Gandhi to the continued Tamil civilian casualties which continue to happen there. This is wrong. India’s response to the mistake of the LTTE was to ban the organisation and draw itself out of the conflict. What you are connecting of the assassination to the casualties is not correct. The casualties are happening at both ends. There have been quite a few Sinhala casualties as well as many Tamil casualties. So this is part of the war. Drawing the Indian Govt. and congress party into this is wrong.

Question:
3.
When Sonia Gandhi and Priyanka can consider pardoning Nalini who was directly involved in Rajiv Gandhi’s assasination, why can’t Indian government pardon unconnected Srilankan Tamil people and help them in a humanitarian way.

Answer:
Nalini’s pardon was only from Priyankas side. The Congress party and the government and the nation have not forgotten/forgiven the assassination. LTTE does not regret the assassination (despite the claims by late Anton Balasingham). They feel bad about the fact that they got further alienated because of this. That is the only thing – otherwise they have not truly regretted. The attack on Rajiv Gandhi’s statue is some indication of what the sympathisers feel for the incidence.

Question:
Is it because, as of now Srilankan people’s only savior is LTTE?

Answer:
India genuinely feels for the plight of the Sri Lankan Tamils. We are sending in a lot of aid and help. However it is wrong to say that the only saviour of the Sri Lankan tamils is the LTTE. This is wrong. There are other Tamil political parties like EPRLF, PLOTE etc. which participated in the multi-party elections in east Sri Lanka and won as well. They are running the local government there. LTTE have always tried to be the single representative of the Sri Lankan Tamils by eliminating/assassinating other representatives of the Tamils. This has always been wrong. This is one more reason why the LTTE should be crushed totally and other Tamil political parties should be nurtured to bring about a true democratic multi-party system with enough powers devolvedagain within the ambit of the Sri Lankan federal framework.

 

Nagarajan Says:
October 28, 2008 at 4:02 pm

“India’s response to the mistake of the LTTE was to ban the organisation and draw itself out of the conflict”. – That is the objective of Srilankan army also. But to this end helping the Srilankan army is not correct. We tried once and failed miserably.

“The casualties are happening at both ends. There have been quite a few Sinhala casualties as well as many Tamil casualties.” – There is a difference between ‘quite a few’ and ‘many’; and again between army casualty and civilian casualty.

“Drawing the Indian Govt. and congress party into this is wrong.” – I did not draw Congress party into the discussion. Now I can say, Tamilnadu Congress is conspicuous by its absence of any sympathy towards Srilankan Tamils. Is it super patriotism or pure and simple sycophancy?

“The Congress party and the government and the nation have not forgotten/forgiven the assassination. LTTE does not regret the assassination (despite the claims by late Anton Balasingham).” – Yes, there are others outside the congress and government who have not forgotten Rajiv’s assassination, including me. Rajiv was our prime minister not only congress’s.

“The attack on Rajiv Gandhi’s statue is some indication of what the sympathisers feel for the incidence.” – True. I fear Rajiv’s sacrifice in obtaining a solution to this problem may come to a naught, by the present attitude of congress party.

“India genuinely feels for the plight of the Sri Lankan Tamils.” – Is it so? Then why it needed such a show of sympathy from Tamilnadu and a threat from DMK to make even a symbolic move towards peace and relief?

“There are other Tamil political parties like EPRLF, PLOTE etc. which participated in the multi-party elections in east Sri Lanka and won as well.” – Yes, but I do not hear about them much nowadays. Is Govt. (or Congress party!) in touch with them?. What do they feel about the present conflict?

Apart from these comments I agree with all the other things written by you (say about 80%), including the suggested solution. Thanks for taking my comments seriously and replying. Happy Diwali and Jai Hind!

 

darashikoh Says:
October 29, 2008 at 4:47 am

Question: “India’s response to the mistake of the LTTE was to ban the organisation and draw itself out of the conflict”. – That is the objective of Srilankan army also. But to this end helping the Srilankan army is not correct. We tried once and failed miserably.

Answer: India’s response was due to LTTEs action. Between the period of IPKF withdrawal and assassination – India was still involved politically in negotiations etc. However post assassination – we withdrew completely. This was solely because of the mistake done by the LTTE. That Sri Lanka also desired that outcome is incidental. Besides we need to remember that the sovereignty of that nation has to be respected. In fact even now – despite whatever overtures we are doing of pushing for a political solution/humanitarian aid – it is well within the integrity of the Sri Lankan nation and still respects its sovereignty. We need to remember that we cannot exert direct pressure on them. We can only issue demarches and summon their commissioner. Beyond that we can extend aid and material.

Question: “The casualties are happening at both ends. There have been quite a few Sinhala casualties as well as many Tamil casualties.” – There is a difference between ‘quite a few’ and ‘many’; and again between army casualty and civilian casualty.

Answer: Yes I agree with you on that. I don’t deny that. But there have been Sinahalese civilian casualties as well – due to bombings from the LTTE. HoweverI agree with you that the scale of the Tamil civilian casualties is much higher.

Question: “Drawing the Indian Govt. and congress party into this is wrong.” – I did not draw Congress party into the discussion. Now I can say, Tamilnadu Congress is conspicuous by its absence of any sympathy towards Srilankan Tamils. Is it super patriotism or pure and simple sycophancy?

Answer: The Government of India(GOI) along with the foreign minister of Sri Lanka have issued a joint statement expressing concern on the humanitarian crisis, escalated by these on going tensions. Prior to that, they issued a demarche to the commissioner to highlight India’s concern in this regard. I agree with you that all this happened because of the flexing of the political muscle of Tamil parties in Tamil Nadu. That the Tamil Nadu Congress party was conspicuous – well I agree with you that they did not take any stand at all (whereas even the AIADMK took a definite stand on this issue). However our concern shown at the national level by GOI – to some extent mitigates it. But you are overall right on this.

Question: “India genuinely feels for the plight of the Sri Lankan Tamils.” – Is it so? Then why it needed such a show of sympathy from Tamilnadu and a threat from DMK to make even a symbolic move towards peace and relief?

Answer: Yes I agree with you that without the threat this would not have been highlighted.

Question: “There are other Tamil political parties like EPRLF, PLOTE etc. which participated in the multi-party elections in east Sri Lanka and won as well.” – Yes, but I do not hear about them much nowadays. Is Govt. (or Congress party!) in touch with them?. What do they feel about the present conflict?

Answer: There was an interview given by Sivanesathurai Santhirakanthan – the chief minister of East Sri Lanka and head of Tamil Makkal Viduthalai Puligal (TMVP) – in The Hindu – dated 27th October.

http://blogs.thehindu.com/delhi/?p=4918

They participated in the election – won it and are now running the government. They have some concerns (which all governments do) – which they hope would be resolved in the near future. However the democratic process has been a success – and time will tell about the magnitude of the success. Elections, democracy, peace, development – this is the way. In fact just yesterday 4 of their members were killed by the LTTE in Batticaloa and 5 more were kidnapped. The LTTE continues with its agenda of trying to be the sole representative of the Sri Lankan Tamil cause. They don’t want to give democracy and peace a chancewhen it excludes them. http://www.defence.lk/new.asp?fname=20081028_06

Please also read the interview of President Mahinda Rajapaksa in today’s Hindu:

http://www.hindu.com/2008/10/29/stories/2008102955181100.htm

I liked your last line. Happy Diwali and Jain Hind to you too!!!