The law J = σE, where J is current density, σ is electrical conductivity and E is field strength is ?->(Show Answer!)

1. The law J = σE, where J is current density, σ is electrical conductivity and E is field strength is

Write Comment

Comments

Tags

Show Similar Question And Answers

QA->Which element is with the highest electrical conductivity?....

QA->If the current in the core decreases; what will the strength of the magnetic field be?....

QA->If the current in the core decreases, what will the strength of the magnetic field be?....

QA->The instrument used for measuring the density or relative density of liquids?....

QA->Orbital interaction between the sigma bonds of a substituent group and a neighboring pi orbital is known as :....

MCQ-> In a modern computer, electronic and magnetic storage technologies play complementary roles. Electronic memory chips are fast but volatile (their contents are lost when the computer is unplugged). Magnetic tapes and hard disks are slower, but have the advantage that they are non-volatile, so that they can be used to store software and documents even when the power is off.In laboratories around the world, however, researchers are hoping to achieve the best of both worlds. They are trying to build magnetic memory chips that could be used in place of today’s electronics. These magnetic memories would be nonvolatile; but they would also he faster, would consume less power, and would be able to stand up to hazardous environments more easily. Such chips would have obvious applications in storage cards for digital cameras and music- players; they would enable handheld and laptop computers to boot up more quickly and to operate for longer; they would allow desktop computers to run faster; they would doubtless have military and space-faring advantages too. But although the theory behind them looks solid, there are tricky practical problems and need to be overcome.Two different approaches, based on different magnetic phenomena, are being pursued. The first, being investigated by Gary Prinz and his colleagues at the Naval Research Laboratory (NRL) in Washington, D.c), exploits the fact that the electrical resistance of some materials changes in the presence of magnetic field— a phenomenon known as magneto- resistance. For some multi-layered materials this effect is particularly powerful and is, accordingly, called “giant” magneto-resistance (GMR). Since 1997, the exploitation of GMR has made cheap multi-gigabyte hard disks commonplace. The magnetic orientations of the magnetised spots on the surface of a spinning disk are detected by measuring the changes they induce in the resistance of a tiny sensor. This technique is so sensitive that it means the spots can be made smaller and packed closer together than was previously possible, thus increasing the capacity and reducing the size and cost of a disk drive. Dr. Prinz and his colleagues are now exploiting the same phenomenon on the surface of memory chips, rather spinning disks. In a conventional memory chip, each binary digit (bit) of data is represented using a capacitor-reservoir of electrical charge that is either empty or fill -to represent a zero or a one. In the NRL’s magnetic design, by contrast, each bit is stored in a magnetic element in the form of a vertical pillar of magnetisable material. A matrix of wires passing above and below the elements allows each to be magnetised, either clockwise or anti-clockwise, to represent zero or one. Another set of wires allows current to pass through any particular element. By measuring an element’s resistance you can determine its magnetic orientation, and hence whether it is storing a zero or a one. Since the elements retain their magnetic orientation even when the power is off, the result is non-volatile memory. Unlike the elements of an electronic memory, a magnetic memory’s elements are not easily disrupted by radiation. And compared with electronic memories, whose capacitors need constant topping up, magnetic memories are simpler and consume less power. The NRL researchers plan to commercialise their device through a company called Non-V olatile Electronics, which recently began work on the necessary processing and fabrication techniques. But it will be some years before the first chips roll off the production line.Most attention in the field in focused on an alternative approach based on magnetic tunnel-junctions (MTJs), which are being investigated by researchers at chipmakers such as IBM, Motorola, Siemens and Hewlett-Packard. IBM’s research team, led by Stuart Parkin, has already created a 500-element working prototype that operates at 20 times the speed of conventional memory chips and consumes 1% of the power. Each element consists of a sandwich of two layers of magnetisable material separated by a barrier of aluminium oxide just four or five atoms thick. The polarisation of lower magnetisable layer is fixed in one direction, but that of the upper layer can be set (again, by passing a current through a matrix of control wires) either to the left or to the right, to store a zero or a one. The polarisations of the two layers are then either the same or opposite directions.Although the aluminum-oxide barrier is an electrical insulator, it is so thin that electrons are able to jump across it via a quantum-mechanical effect called tunnelling. It turns out that such tunnelling is easier when the two magnetic layers are polarised in the same direction than when they are polarised in opposite directions. So, by measuring the current that flows through the sandwich, it is possible to determine the alignment of the topmost layer, and hence whether it is storing a zero or a one.To build a full-scale memory chip based on MTJs is, however, no easy matter. According to Paulo Freitas, an expert on chip manufacturing at the Technical University of Lisbon, magnetic memory elements will have to become far smaller and more reliable than current prototypes if they are to compete with electronic memory. At the same time, they will have to be sensitive enough to respond when the appropriate wires in the control matrix are switched on, but not so sensitive that they respond when a neighbouring elements is changed. Despite these difficulties, the general consensus is that MTJs are the more promising ideas. Dr. Parkin says his group evaluated the GMR approach and decided not to pursue it, despite the fact that IBM pioneered GMR in hard disks. Dr. Prinz, however, contends that his plan will eventually offer higher storage densities and lower production costs.Not content with shaking up the multi-billion-dollar market for computer memory, some researchers have even more ambitious plans for magnetic computing. In a paper published last month in Science, Russell Cowburn and Mark Well and of Cambridge University outlined research that could form the basis of a magnetic microprocessor — a chip capable of manipulating (rather than merely storing) information magnetically. In place of conducting wires, a magnetic processor would have rows of magnetic dots, each of which could be polarised in one of two directions. Individual bits of information would travel down the rows as magnetic pulses, changing the orientation of the dots as they went. Dr. Cowbum and Dr. Welland have demonstrated how a logic gate (the basic element of a microprocessor) could work in such a scheme. In their experiment, they fed a signal in at one end of the chain of dots and used a second signal to control whether it propagated along the chain.It is, admittedly, a long way from a single logic gate to a full microprocessor, but this was true also when the transistor was first invented. Dr. Cowburn, who is now searching for backers to help commercialise the technology, says he believes it will be at least ten years before the first magnetic microprocessor is constructed. But other researchers in the field agree that such a chip, is the next logical step. Dr. Prinz says that once magnetic memory is sorted out “the target is to go after the logic circuits.” Whether all-magnetic computers will ever be able to compete with other contenders that are jostling to knock electronics off its perch — such as optical, biological and quantum computing — remains to be seen. Dr. Cowburn suggests that the future lies with hybrid machines that use different technologies. But computing with magnetism evidently has an attraction all its own.In developing magnetic memory chips to replace the electronic ones, two alternative research paths are being pursued. These are approaches based on:
....

MCQ->The law J = σE, where J is current density, σ is electrical conductivity and E is field strength is....

MCQ-> The current debate on intellectual property rights (IPRs) raises a number of important issues concerning the strategy and policies for building a more dynamic national agricultural research system, the relative roles of public and private sectors, and the role of agribusiness multinational corporations (MNCs). This debate has been stimulated by the international agreement on Trade Related Intellectual Property Rights (TRIPs), negotiated as part of the Uruguay Round. TRIPs, for the first time, seeks to bring innovations in agricultural technology under a new worldwide IPR regime. The agribusiness MNCs (along with pharmaceutical companies) played a leading part in lobbying for such a regime during the Uruguay Round negotiations. The argument was that incentives are necessary to stimulate innovations, and that this calls for a system of patents which gives innovators the sole right to use (or sell/lease the right to use) their innovations for a specified period and protects them against unauthorised copying or use. With strong support of their national governments, they were influential in shaping the agreement on TRIPs, which eventually emerged from the Uruguay Round. The current debate on TRIPs in India - as indeed elsewhere - echoes wider concerns about ‘privatisation’ of research and allowing a free field for MNCs in the sphere of biotechnology and agriculture. The agribusiness corporations, and those with unbounded faith in the power of science to overcome all likely problems, point to the vast potential that new technology holds for solving the problems of hunger, malnutrition and poverty in the world. The exploitation of this potential should be encouraged and this is best done by the private sector for which patents are essential. Some, who do not necessarily accept this optimism, argue that fears of MNC domination are exaggerated and that farmers will accept their products only if they decisively outperform the available alternatives. Those who argue against agreeing to introduce an IPR regime in agriculture and encouraging private sector research are apprehensive that this will work to the disadvantage of farmers by making them more and more dependent on monopolistic MNCs. A different, though related apprehension is that extensive use of hybrids and genetically engineered new varieties might increase the vulnerability of agriculture to outbreaks of pests and diseases. The larger, longer-term consequences of reduced biodiversity that may follow from the use of specially bred varieties are also another cause for concern. Moreover, corporations, driven by the profit motive, will necessarily tend to underplay, if not ignore, potential adverse consequences, especially those which are unknown and which may manifest themselves only over a relatively long period. On the other hand, high-pressure advertising and aggressive sales campaigns by private companies can seduce farmers into accepting varieties without being aware of potential adverse effects and the possibility of disastrous consequences for their livelihood if these varieties happen to fail. There is no provision under the laws, as they now exist, for compensating users against such eventualities. Excessive preoccupation with seeds and seed material has obscured other important issues involved in reviewing the research policy. We need to remind ourselves that improved varieties by themselves are not sufficient for sustained growth of yields. in our own experience, some of the early high yielding varieties (HYVs) of rice and wheat were found susceptible to widespread pest attacks; and some had problems of grain quality. Further research was necessary to solve these problems. This largely successful research was almost entirely done in public research institutions. Of course, it could in principle have been done by private companies, but whether they choose to do so depends crucially on the extent of the loss in market for their original introductions on account of the above factors and whether the companies are financially strong enough to absorb the ‘losses’, invest in research to correct the deficiencies and recover the lost market. Public research, which is not driven by profit, is better placed to take corrective action. Research for improving common pool resource management, maintaining ecological health and ensuring sustainability is both critical and also demanding in terms of technological challenge and resource requirements. As such research is crucial to the impact of new varieties, chemicals and equipment in the farmer’s field, private companies should be interested in such research. But their primary interest is in the sale of seed materials, chemicals, equipment and other inputs produced by them. Knowledge and techniques for resource management are not ‘marketable’ in the same way as those inputs. Their application to land, water and forests has a long gestation and their efficacy depends on resolving difficult problems such as designing institutions for proper and equitable management of common pool resources. Public or quasi-public research institutions informed by broader, long-term concerns can only do such work. The public sector must therefore continue to play a major role in the national research system. It is both wrong and misleading to pose the problem in terms of public sector versus private sector or of privatisation of research. We need to address problems likely to arise on account of the public-private sector complementarity, and ensure that the public research system performs efficiently. Complementarity between various elements of research raises several issues in implementing an IPR regime. Private companies do not produce new varieties and inputs entirely as a result of their own research. Almost all technological improvement is based on knowledge and experience accumulated from the past, and the results of basic and applied research in public and quasi-public institutions (universities, research organisations). Moreover, as is increasingly recognised, accumulated stock of knowledge does not reside only in the scientific community and its academic publications, but is also widely diffused in traditions and folk knowledge of local communities all over. The deciphering of the structure and functioning of DNA forms the basis of much of modern biotechnology. But this fundamental breakthrough is a ‘public good’ freely accessible in the public domain and usable free of any charge. Various techniques developed using that knowledge can however be, and are, patented for private profit. Similarly, private corporations draw extensively, and without any charge, on germplasm available in varieties of plants species (neem and turmeric are by now famous examples). Publicly funded gene banks as well as new varieties bred by public sector research stations can also be used freely by private enterprises for developing their own varieties and seek patent protection for them. Should private breeders be allowed free use of basic scientific discoveries? Should the repositories of traditional knowledge and germplasm be collected which are maintained and improved by publicly funded organisations? Or should users be made to pay for such use? If they are to pay, what should be the basis of compensation? Should the compensation be for individuals or (or communities/institutions to which they belong? Should individual institutions be given the right of patenting their innovations? These are some of the important issues that deserve more attention than they now get and need serious detailed study to evolve reasonably satisfactory, fair and workable solutions. Finally, the tendency to equate the public sector with the government is wrong. The public space is much wider than government departments and includes co- operatives, universities, public trusts and a variety of non-governmental organisations (NGOs). Giving greater autonomy to research organisations from government control and giving non- government public institutions the space and resources to play a larger, more effective role in research, is therefore an issue of direct relevance in restructuring the public research system.Which one of the following statements describes an important issue, or important issues, not being raised in the context of the current debate on IPRs?
....

MCQ-> Read the following passage carefully and answer the questions given at the end. When Ratan Tata moved the Supreme Court, claiming his right to privacy had been violated, he called Harish Salve. The choice was not surprising. The former solicitor general had been topping the legal charts ever since he scripted a surprising win for Mukesh Ambani against his brother Anil. That dispute set the gold standard for legal fees. On Mukesh’s side were Salve, Rohinton Nariman, and Abhishek Manu Singhvi. The younger brother had an equally formidable line-up led by Ram Jethmalani and Mukul Rohatgi.The dispute dated back three-and-a-half years to when Anil filed case against his brother for reneging on an agreement to supply 28 million cubic metres of gas per day from its Krishna-Godavari basin fields at a rate of $ 2.34 for 17 years. The average legal fee was Rs. 25 lakh for a full day's appearance, not to mention the overnight stays at Mumbai's five-star suites, business class travel, and on occasion, use of the private jet. Little wonder though that Salve agreed to take on Tata’s case pro bono. He could afford philanthropy with one of India’s wealthiest tycoons.The lawyers’ fees alone, at a conservative estimate, must have cost the Ambanis at least Rs. 15 crore each. Both the brothers had booked their legal teams in the same hotel, first the Oberoi and, after the 26/ ll Mumbai attacks, the Trident. lt’s not the essentials as much as the frills that raise eyebrows. The veteran Jethmalani is surprisingly the most modest in his fees since he does not charge rates according to the strength of the client's purse. But as the crises have multiplied, lawyers‘fees have exploded.The 50 court hearings in the Haldia Petrochemicals vs. the West Bengal Government cost the former a total of Rs. 25 crore in lawyer fees and the 20 hearings in the Bombay Mill Case, which dragged on for three years, cost the mill owners almost Rs. 10 crore. Large corporate firms, which engage star counsels on behalf of the client, also need to know their quirks. For instance, Salve will only accept the first brief. He will never be the second counsel in a case. Some lawyers prefer to be paid partly in cash but the best are content with cheques. Some expect the client not to blink while picking up a dinner tab of Rs. 1.75 lakh at a Chennai five star. A lawyer is known to carry his home linen and curtains with him while travelling on work. A firm may even have to pick up a hot Vertu phone of the moment or a Jaeger-LeCoutre watch of the hour to keep a lawyer in good humour.Some are even paid to not appear at all for the other side - Aryama Sundaram was retained by Anil Ambani in the gas feud but he did not fight the case. Or take Raytheon when it was fighting the Jindals. Raytheon had paid seven top lawyers a retainer fee of Rs. 2.5 lakh each just to ensure that the Jindals would not be able to make a proper case on a taxation issue. They miscalculated when a star lawyer fought the case at the last minute. “I don’t take negative retainers”, shrugs Rohatgi, former additional solicitor general. “A Lawyer’s job is to appear for any client that comes to him. lt’s not for the lawyers to judge if a client is good or bad but the court”. Indeed. He is, after all, the lawyer who argued so famously in court that B. Ramalinga Raju did not ‘fudge any account in the Satyam Case. All he did was “window dressing”.Some high profile cases have continued for years, providing a steady source of income, from the Scindia succession battle which dates to 1989, to the JetLite Sahara battle now in taxation arbitration to the BCCI which is currently in litigation with Lalit Modi, Rajasthan Royals and Kings XI Punjab.Think of the large law firms as the big Hollywood studios and the senior counsel as the superstar. There are a few familiar faces to be found in most of the big ticket cases, whether it is the Ambani gas case, Vodafone taxation or Bombay Mills case. Explains Salve, “There is a reason why we have more than one senior advocate on a case. When you're arguing, he’s reading the court. He picks up a point or a vibe that you may have missed.” Says Rajan Karanjawala, whose firm has prepared the briefs for cases ranging from the Tata's recent right to privacy case to Karisma Kapoor’s divorce, “The four jewels in the crown today are Salve, Rohatgi, Rohinton Nariman and Singhvi. They have replaced the old guard of Fali Nariman, Soli Sorabjee, Ashok Desai and K.K. Venugopal.” He adds, “The one person who defies the generational gap is Jethmalani who was India's leading criminal lawyer in the 1960s and is so today.”The demand for superstar lawyers has far outstripped the supply. So a one-man show by, say, Rohatgi can run up billings of Rs. 40 crore, the same as a mid-sized corporate law firm like Titus and Co that employs 28 juniors. The big law filik such as AZB or Amarchand & Mangaldas or Luthra & Luthra have to do all the groundwork for the counsel, from humouring the clerk to ensure the A-lister turns up on the hearing day to sourcing appropriate foreign judgments in emerging areas such as environmental and patent laws. “We are partners in this. There are so few lawyers and so many matters,” points out Diljeet Titus.As the trust between individuals has broken down, governments have questioned corporates and corporates are questioning each other, and an array of new issues has come up. The courts have become stronger. “The lawyer,” says Sundaram, with the flourish that has seen him pick up many Dhurandhares and Senakas at pricey art auctions, “has emerged as the modern day purohit.” Each purohit is head priest of a particular style. Says Karanjawala, “Harish is the closest example in today's bar to Fali Nariman; Rohinton has the best law library in his brain; Mukul is easily India's busiest lawyer while Manu Singhvi is the greatest multi-tasker.” Salve has managed a fine balancing act where he has represented Mulayam Singh Yadav and Mayawati, Parkash Singh Badal and Amarinder Singh, Lalit Modi and Subhash Chandra and even the Ambani brothers, of course in different cases. Jethmalani is the man to call for anyone in trouble. In judicial circles he is known as the first resort for the last resort. Even Jethmalani’s junior Satish Maneshinde, who came to Mumbai in I993 as a penniless law graduate from Karnataka, shot to fame (and wealth) after he got bail for Sanjay Dutt in 1996. Now he owns a plush office in Worli and has become a one-stop shop for celebrities in trouble.Which of the following is not true about Ram Jethmalani?
....

MCQ->In metals the thermal conductivity K and electrical conductivity σ are related as (K/σT) = L, L is known as....