2019-07-18
There is a very interesting kind of crystal that produces different charges at both ends when you squeeze or stretch it. This effect is called the piezoelectric effect. A crystal that produces a piezoelectric effect is called a piezoelectric crystal. Crystal (α-quartz) is a well-known piezoelectric crystal.
If pressure is applied to the sliced piece on the crystal crystal in a certain direction, an electric charge will be generated on the sheet. If the sheet is stretched in the opposite direction, a charge will also appear on the sheet, but the sign is reversed. The greater the force of extrusion or stretching, the more charge there will be on the crystal. If the electrodes are plated on both ends of the sheet and are supplied with alternating current, the sheet will be periodically elongated or shortened, i.e., begins to vibrate. This inverse piezoelectric effect has been widely used in science and technology. Piezoelectric quartz flakes can be made from crystal, which is only a few square millimeters in area and only a few tenths of a millimeter in thickness. Don't underestimate this small chip, it plays a huge role in radio technology. As mentioned earlier, in an alternating electric field, the vibration frequency of such a sheet is not changed at all. This kind of stable vibration is necessary for controlling the frequency in radio technology. Many electrical appliances such as color TVs in your home have filters made of piezoelectric wafers to ensure the clarity of images and sounds. There is a core component in the quartz electronic watch that you wear on your hand called a quartz vibrator. It is this key component that guarantees a higher travel accuracy of quartz watches than other mechanical watches.
Instruments equipped with piezoelectric crystal components enable technicians to study the changes in pressure in steam engines, internal combustion engines and various chemical equipment. The piezoelectric crystal can even measure the pressure of the fluid in the pipeline, the pressure that the cannon barrel can withstand when launching the projectile, and the instantaneous pressure when the bomb explodes.
Piezoelectric crystals are also widely used in the reproduction, recording and transmission of sound. A piezoelectric wafer mounted on a microphone converts the vibration of the sound into a change in current. As soon as the sound wave hits the piezoelectric sheet, an electric charge is generated on the electrodes at both ends of the sheet, and the size and sign thereof change with the sound. The change in charge on the piezoelectric wafer can be turned into a distant place by radio waves through electronic devices. These radio waves are received by the radio and reverberated into the air by the vibration of the piezoelectric crystal sheets placed on the radio speakers. Is it possible to say that the piezoelectric wafer in the microphone can "sound" the sound, and the piezoelectric crystal on the speaker will "speak" or "sing".
