G V Joshi
In the 1840s, the well-known scientist Michael Faraday, (1791 to 1867), in one of his science lectures, demonstrated a strange observation. He pushed a magnet into the hollow centre of a spiral coil of metallic wire connected to a galvanometer that would record the presence of an electric current.
There was no current in the wire to begin with, but as the magnet was inserted, the galvanometer’s needle moved to one side of the scale, showing that an electric current was flowing.
As the magnet was withdrawn, the needle swung in the other direction, showing that the current was now flowing the other way. When the magnet was held motionless within the coil, no current flowed at all.
After the lecture, a listener came to Faraday and asked, “But of what practical use can this be?” Faraday replied, “Sir, of what use is a newborn baby?”
Faraday made use of this observation to develop the electric generator (dynamo), which, for the first time, made it possible to produce electricity cheaply and in quantity.
Today after nearly 150 years Faraday’s newborn baby has grown into a giant without which we can’t live, and is still growing.
Whenever you want to heat water for tea or coffee or starting cooking, you take a gas lighter and light the gas. How does the gas lighter work?
A little spring-loaded hammer hits a crystal and generates a spark which carries a few thousand volts of minute amount of electricity across the lighter tip. This spark, which lights the gas, is created by piezoelectric effect.
What is Piezoelectric Effect? In 1880 Pierre Curie, well-known for discovery of radium (along with Marie Curie, his wife) and his brother Jacques Curie discovered that there are certain crystals that become electrically charged when mechanical force is applied on them.
But the first patent application for a piezoelectric lighter for lighting cooking gas was submitted in 1962 only… Piezoelectric crystals have found many more uses now.
Quartz crystals have piezoelectric properties, meaning that they are capable of changing a mechanical force into electricity, or an electric current into a mechanical force.
A slice, or wafer, of quartz crystal will generate an electric current when it is subjected to pressure. Conversely, a wafer connected in an alternating electric circuit will expand and contract, or vibrate at a fixed frequency.
The frequency of the quartz crystal oscillator is determined by its cut and shape. This frequency depends on the thickness of the wafer. Thin wafers oscillate at higher frequencies than thick ones.
Quartz crystal wafers could be used to control the frequencies of oscillating electric circuits in radio transmitters. They could also used to convert electric signals into sound waves in devices such as sonar and ultrasonic generators. In such devices as hearing aids and submarine detectors, quartz crystals convert weak sound waves into electric current, which is then amplified and reconverted into sound waves.
These properties of quartz crystals are known for over a century.
It was only in 1926 only that a radio transmitter in New York City (US) used a quartz crystal unit to control its frequency. Within a few years all radio stations went to crystal control.
Quartz crystals were first used as a time standard by Warren Marrison, who invented the first quartz clock in 1927. A method for mass-producing quartz crystals for watches was invented only in the early 1970s by Juergen Staudte.
Marrison’s clock proved to be more accurate than previous time keepers. Marrison and others demonstrated that the quartz oscillator used in this way was more accurate than the best existing mechanical clocks used in astronomical observatories as time keepers.
During the 1940s, time standard laboratories throughout the world switched from mechanical clocks to quartz. The fundamental standard of time remained the rotation of the earth relative to the stars, but quartz clocks confirmed that the earth was an unreliable timekeeper. However, quartz clocks have now been replaced by atomic clocks.
The application of the vibration of quartz crystal to wrist watches was new. And going from a huge quartz clock occupying a small room to a wrist watch, required some giant leaps in technology.
In 1962, a number of Swiss watchmakers put aside their own differences and pooled nearly 6 million dollars to develop an accurate and reliable electronic wrist watch based on quartz.
In December 1967, they produced a quartz wrist watch that proved to be the most accurate ever made. However, shortly afterwards, the Japanese firm of Seiko came out with its own electronic quartz wrist watch. Since then the Japanese, moving up from nowhere in the watchmaking field, have come close to the top.
The idea of using atoms to measure time was first suggested by Lord Kelvin in 1879. Magnetic resonance, developed in the 1930s by Dr I.I. Rabi, became the practical method for doing this. In 1945, Rabi first publicly suggested that atoms might be used as the basis of a clock.
The first atomic clock was an ammonia based device built in 1949 in the US. It was less accurate than the then available quartz clocks, but served to demonstrate the concept. The first accurate atomic clock, based caesium atom, was built by Louis Essen in 1955 in the UK. Since then atomic clocks are becoming better and better every year. As of 2011, the latest atomic clock is expected to neither gain nor lose a second in more than 138 million years.
The development of atomic clocks has led to Global Positioning System, and applications in the Internet, which depend critically on accurate time measurement. Atomic clocks are used in many scientific disciplines, such as for long-baseline interferometry in radio-astronomy.
Today, all of us use computers which depend upon binary arithmetic, Boolean Algebra and transistors.
The Indian mathematician Pingala who lived a few centuries before Christ presented the first known description of a binary number system. The modern binary number system was developed by the German mathematician Gottfried Leibniz, the inventor of differential calculus, in 1679. The system only uses 0 and 1, like the modern binary numeral system.
In 1854, British mathematician George Boole developed an algebraic system of logic that became known as Boolean algebra, which was to become instrumental in the design of digital computers.
The research work which led to the invention and development of transistors followed by their use in integrated circuits (ICs) used in computers was carried out by the physicists working at the Bell Labs in the US in 1950s.They could not foresee their million applications within the next 50 years.
There are many more similar examples where scientists could not foresee the future applications which came up much later. In fact, unless scientists study fundamental sciences and gather knowledge, people will continue to have new problems but no solutions. For today’s science is tomorrow’s application — and, most of all; it is humanity’s greatest adventure. (PTI)
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