My greeting to all the techno-enthusiast and problem decoders out there. This is my first post on HOW STUFF WORKS!.Hope you like it. Please leave your feedback in the comments section. Also please notify me about any topic if you want to know about it. Enough of this, so now without wasting any time lets get started.
INTRODUCTION
Ever wondered how the clock ticks and maintains its constant motion or how a cigarette lighter ignites?? The answer to this is piezoelectricity!!! The quartz crystal that is used to maintain the time of the watch is a piezoelectric substance. SO NOW THE QUESTION IS: WHAT IS A PIEZOELECRIC SUBSTANCE??
Piezoelectric means electricity resulting from pressure. It is derived from the Greek word
piezo or
pie(πιέζειν), which means to squeeze or press, and
electric or
electron (
ήλεκτρον), which stands for amber, an ancient source of charge.
Piezoelectricity was discovered in 1880 by French physicists
Jacques and
Pierre Curie. The Curies, however, did not predict the converse piezoelectric effect.
The converse effect was mathematically deduced from fundamental
thermodynamic principles by
Gabriel Lippmann in 1881.
The Curies immediately confirmed the existence of the converse effect,
and went on to obtain quantitative proof of the complete reversibility of electro-elasto-mechanical deformations.
So it is this electricity that is generated between the poles of the quartz crystal in your watch that generates a electric field and keeps your clock ticking.
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| A PIEZOELECTRIC SUBSTANCE |
HOW THIS WORKS??
The piezoelectric effect
is understood as the linear electromechanical interaction between the
mechanical and the electrical state in crystalline materials with no inversion symmetry .The piezoelectric effect is a reversible process
in that materials exhibiting the direct piezoelectric effect (the
internal generation of electrical charge resulting from an applied
mechanical force)
also exhibit the reverse piezoelectric effect (the internal generation
of a mechanical strain resulting from an applied electrical field).
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| ILLUSTRATION OF THE EFFECT |
For
example, .
lead zirconate titanate
(also popularly known as PZT)
crystals will generate measurable piezoelectricity when their static
structure is deformed by about 0.1% of the original dimension.(however
this change of dimension is not noticeable, but it can generate a voltage
of up to 26V!! ISNT THAT GREAT!!)
Conversely, those same crystals will change about 0.1% of their static
dimension when an external electric field is applied to the material.
The inverse piezoelectric effect is used in production of ultrasonic
sound waves.
So in your wall clock/watch the power source or the battery is used to strike a piezoelectric substance(that is QUARTZ mostly) with the help of a small hammer, which in turn generates a field between the pole pieces of the crystal and help in maintaining motion.
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| VOLTAGE GENERATION FROM A PIEZOELECTRIC MATERIAL( |
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| The extent of deformation is greatly exaggerated) | | | |
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| PIEZOELECTRIC PLATES USED TO CONVERT AUDIO SIGNALS TO SOUND WAVES |
APPLICATIONS
Piezoelectric substance find there use in our day to day life(the blog also aims at creating awareness about day to day stuff!!) ranging from gas lighter, speakers, guitar pickups to clocks, buzzers and other sensors as mentioned above. The most common piezoelectric substance that we use daily is sucrose( table sugar) but i am sure you haven't paid any notice to its this unique property up til now!!
Even rochelle salt serves as a great piezoelectric material and could easily be used as guitar pickup(try making it!!)
Other piezoelectric substances include rochelle salt (i have enclosed a link for the readers who would lyk to manufacture it at home), lead zirconate titanate (PZT), quartz, tourmaline(typically used as a polarizer), topaz(a typical gem, mostly aluminum oxide) find there specific application in manufacture of various transducers, sensors and actuators depending upon there dipole moment and dielectric strength.
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| METAL DISC WITH PIEZOELECTRIC DISK ATTACHED TO IT, USED IN BUZZERS |
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| A PIEZOELECTRIC DISC, USED AS GUITAR PICKUPS |
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Those fellow readers who would like to manufacture rochelle salt at home, herer the link-
http://rimstar.org/materials/piezo/how_to_make_rochelle_salt_piezoelectric_crystal.htm
Please leave your suggestions, queries or anything else that you would like to know!!
Till then SAYONARA!!
