PIEZOELECTRIC EFFECT
1. Context
Piezoelectrics are materials with a particularly interesting property — they can effectively create a surplus and a deficiency of electrons when they are under pressure. The reason these materials can do this is because the atoms in such a material are arranged in a slightly funny periodic pattern
2. What is an Electric Spark?
- A spark is essentially the movement of an electric charge through the air between two points, one with an excess of electrons and the other with a shortage. This imbalance in electron quantities can arise due to various reasons. Sometimes, it is deliberately created, such as in a battery, which powers everything from remote controls to electric vehicles.
- The point with an excess of electrons is referred to as the negative terminal because electrons carry a negative charge, while the point lacking electrons is called the positive terminal.
- This is why batteries are marked with ‘+’ and ‘-’ signs. In general, electrons, unlike some individuals, are inherently fair and prefer to equalize any imbalance. When given the chance, they move from a region of abundance to one of scarcity.
- This movement of electrons is what creates an electric current when a wire connects the two ends of a battery, enabling devices like fans to rotate or bulbs to illuminate
Natural giant sparks
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3. Piezoelectric Material
- The piezoelectric effect refers to the property of certain materials to produce an electric charge when subjected to mechanical stress. The term "piezoelectric" originates from the Greek words piezein, meaning "to squeeze or press," and piezo, meaning "push."
- A distinctive feature of the piezoelectric effect is its reversibility. This means that materials capable of generating electricity when mechanical stress is applied (direct piezoelectric effect) can also generate mechanical stress when exposed to an electric field (converse piezoelectric effect).
- When mechanical stress is applied to a piezoelectric material, it causes a displacement of the material's positive and negative charge centers, leading to the creation of an external electric field. Conversely, when an external electric field is applied, it can cause the material to either stretch or compress.
- The piezoelectric effect has numerous applications, including sound production and detection, generation of high voltages, electronic frequency generation, microbalances, and precise focusing of optical instruments.
- It is also fundamental to scientific techniques like scanning probe microscopy (e.g., STM, AFM), which provide atomic-level resolution. Beyond scientific uses, the piezoelectric effect is applied in everyday devices, such as serving as the ignition mechanism in cigarette lighters
4. Way Forward
The movement of these flying electrons can ignite a flammable substance. This is why, when the cooking gas is turned on and you press the lighter nearby, it creates a flame on your stove. Occasionally, the pressure applied to the lighter may not be sufficient to generate a spark, requiring multiple attempts until one produces a spark strong enough to ignite the gas. (If you find this topic fascinating and want to explore piezoelectric materials further, a physics course on condensed matter physics could provide valuable insights.)
For Prelims: Electrons, Protons, Nuetrinos
For Mains: GS III - Science & Technology
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Source: The Hindu