Super Conductivity

(Summary of TMH book on Science and Technology for UPSC CSE preparations)

1 . What is Cryogenics? How does it help Doctors? 50 words 
How does it help Physics?
Cryogenics is the study of extremely low temperatures. It include the development of techniques that produce and maintain such temperatures for industrial and scientific use.

Cryogenics has provided doctors with ways to freeze living parts of the body, such as blood and eye corneas, for future use. Other medical uses of cryogenics include freezing organs during operations and destroying diseased tissues.

2. What is absolute zero?
Absolute zero, is theoretically the lowest temperature a gas can reach. It is equivalent to 0 kelvin or minus 273.15 degree Celsius.

3. What is liquid air? What are its industrial uses?
The first industrial use of cryogenics was the production of liquid air, a primary source of liquid oxygen and liquid nitrogen. Certain aircrafts and spacecrafts carry liquid oxygen that can be converted into gaseous form for crews to breathe during long flights. Other uses of liquid oxygen include the manufacture of synthetic gases and treatment of waste paper. Liquid nitrogen serves as a refrigerant.

4 . What is Super Conductivity?
It is the ability of a material to conduct electricity without any losses to resistance. It is a physical property inherent in a variety of metals and ceramics. It is dependent on temperature, that is, a material will not exhibit superconductivity until the temperature is sufficiently low.

5 . What did Onnes do for getting Nobel Prize?
in 1911, the Dutch scientist Onnes cooled mercury to 4K (-269 degree Celsius). At this temperature, the motion of individual atoms nearly ceased. It was then found that there was no electrical resistance in the material.

6 . What are the major application areas of super conductivity? 50 words 400
Superconducting switching devices that control electronic circuits are used in computers. They operate extremely quickly and produce almost no heat. Power lines made of superconducting materials can transmit electricity over long distances without any loss of power from electrical resistance. Superconductors can be used to make electro-magnets that generate large magnetic fields with no energy loss. This could be used for magnetic suspension of high speed trains or Maglev trains.

7 . What is magnetic levitation? 401
Trains can be made to float on strong superconducting magnets, virtually eliminating the friction between the train and the tracks. Thus greatly reduces the cost of operation. Maglev trains can provide sustained speeds greater than 500kmph, limited only by the cost of power to overcome wind resistance.

8 . What is MRI? 401
Magnetic Resonance Imaging (MRI) is a technique based on the principles of nuclear magnetic resonance. MRI is possible in the human body because the body is filled with small biological magnets, the most abundant and responsive of which is the proton, the nucleus of the hydrogen atom.

9 .  How does  MRI help in medicine? 100 words 401
First, the MRI places the body in a steady magnetic field. Then, the MRI stimulates the body with radio waves to change the steady-state orientation of the protons. It then stops the radio waves and detects the body’s electro-magnetic transmissions at a selected frequency. This transmitted signal is used to construct internal images of the body, using principles similar to those developed for CAT scanners.

It is preferred for diagnosing most diseases of the brain and the central nervous system

10 . How do super conductors help Electric Systems? 402
Electric generators made with superconducting wire are far more efficient than conventional generators wound with copper wire. Power utilities have also begun to use superconducting transformers. An ideal application for superconductors would be to employ them in the transmission of electricity to cities.

11 . What are Petaflop computers? How are they different from teraflop computers? 403
A Petaflop is a 1000-trillion floating point operations per second. NASA is currently researching this. A Teraflop computer has only reached speeds of trillions of operations per second.
12 . What s the. IBM Blue Gene/L computer? 403
Currently the fastest computer is the IBM Blue Gene/L, running at a speed of 280.6 teraflops per second.

13 . What is Josephson junction? 403, 404
Josephson examined the quantum nature of superconductivity and proposed the existence of oscillations in electric current flowing through two superconductors separated by a thin insulating layer in a magnetic or electric field (Josephson junction) although according to classical physics, an electric current cannot flow in a circuit that is interrupted by an insulating barrier. This effect, known as the Josephson Effect, is a feature of quantum electron tunnelling. Thus, it is basically the flow of electric current through non-conductive material.

14 . What are the military uses of super conductors?
Significantly smaller motors are being built for naval ships using superconducting wire. It is also used in degaussing naval vessels. Degaussing of a ship’s hull eliminates residual magnetic fields which might otherwise give away a ship’s presence. Efforts are also being made to use superconducting tape as a means of reducing the length of very low frequency antennas employed on submarines.

15 . What are E Bombs?
A controversial use of superconductors may come with the deployment of E-bombs. These are devices that make us of strong, superconductor-derived magnetic fields to create a fast, high-intensity electro-magnetic pulse to disable the enemy’s electronic equipment.

16 . What are SQUIDs ? 404
Superconducting Quantum Interfering Devices (SQUIDS) are among the most sensitive devices. It is essentially an ultrasensitive detector of magnetic flux, made up of a superconducting ring interrupted by one or two Josephson junctions. It is capable of detecting magnetic fields of around 2T. It is required to be kept at a temperature of about 4.2K.

17 . What is Magnetoencephalography? 405
What is a Neuromagnetometer?
With Magnetoencephalography (MEG), the body can be probed to certain depths without the need for the strong magnetic fields associated with MRIs. It is a non-invasive method for recording minute magnetic fields emanating from the brain.

The MEG device is known as a Neuromagnetometer. It consists of a helmet-like instrument which is placed around a subject’s head.

18 . How do we distinguish the mother’s heartbeat from the Fortal
heartbeat ? 405
SQUIDS can measure the minute magnetic fields generated by a baby’s heart. It has the ability to distinguish the mother’s heartbeat from the baby’s. This allows early diagnosis of foetal heart conditions, which could be potentially life-saving.

19 . Mention some of the applications of Josephson devices. 406
Josephson devices can be used in magnetic sensors, gradiometers, oscilloscopes, decoders, analog to digital converters, samplers, microwave amplifiers, micro-processors and RAMs.

20 . What is  a Bolometer? What is its use?
It is an instrument used to measure infrared radiation or any other form of radiation energy. They are now primarily used in the detection of heat energy transmitted from distant sources. In astronomy, it is used to measure the heat of the stars.

21. What is a Quiteron? 407
Most integrated circuits today use standard transistors. A replacement presently being studied is called a quiteron. If two superconducting materials are separated by an insulating material, it is possible for electron pairs to pass through this material without any resistance (Josephson junction). Due to this, changes in resistance caused by changes in voltages can take place in a billionth of a second or less. This performs the same function as a transistor but at much higher speeds.

22. Mention a few Magnetic anomaly Detectors. 100 words 407
In the military context, the developments were based on detection of submarines by aircrafts. The large amounts of magnetic materials in a submarine causes a slight focusing of the earth’s magnetic field. The innovations in superconductors allowed the measurements of these variations in field strength. The process by which the magnetic fields are detected involves SQUID magnetometers. HTSC SQUIDS are being used by the U.S navy for detection of mines and submarines.

A major use of superconductors in geology is mapping magnetic fields. Devices called magnetometers help to detect magnetic anomalies or distinguish between geological features that would otherwise be indistinguishable.

In the biomedical field, they can be used for muscle measurements, measurement of amounts of iron in the system and cardiac measurements.

23 . What are the future prospects of Super Conductors?

They are expected to play a dominant role in well-established fields such as MRI and scientific research, it could also help to battle climate change. It has been calculated that the EU could reduce carbon dioxide emissions by 53 million tons if super-conductors are used in power plants. The future role of superconductors will also depend on the advancements in cryogenics. Materials such as gadolinium-silicon-germanium are expected to make possible compact refrigeration units.


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