Static electricity is an imbalance of electric charges within or on the surface of a material. When objects have equal numbers of positive and negative charges, they are electrically neutral. However, when electrons are transferred from one object to another, an imbalance occurs, creating static electricity.
The triboelectric effect is the main cause of static electricity. When two different materials are rubbed together, electrons transfer from one material to another through friction. For example, when you rub a balloon on your hair, electrons move from your hair to the balloon, leaving the balloon negatively charged and your hair positively charged.
Static charges create electric fields around them. These invisible fields exert forces on other charges. Opposite charges attract each other, while like charges repel. The strength of these forces depends on the amount of charge and the distance between them. This is why a charged balloon can attract small pieces of paper or make your hair stand up.
When static charge builds up to a high enough level, it can suddenly discharge as a spark. This happens when the electric field becomes strong enough to ionize the air molecules between charged objects. The spark you see and hear when touching a doorknob is actually electricity jumping through the air, creating a temporary conductive path.
静电是我们日常生活中常见的物理现象。当物质表面累积了电荷，且这些电荷不发生流动时，就形成了静电。所有物质都由原子组成，原子包含带正电的质子和带负电的电子。正常情况下，正负电荷数量相等，物体呈电中性。
静电最常见的产生方式是摩擦起电。当两个物体相互摩擦时，电子会从一个物体转移到另一个物体。失去电子的物体带正电，获得额外电子的物体带负电。这种电荷分离就是静电产生的基本原理。不同材料的电子结合能力不同，决定了哪个物体会失去电子。
电荷之间的相互作用遵循库仑定律。该定律表明，两个点电荷之间的作用力与它们电荷量的乘积成正比，与距离的平方成反比。同性电荷（正正或负负）相互排斥，异性电荷（正负）相互吸引。这个基本规律解释了静电现象中电荷的行为模式。
电场是电荷周围存在的一种特殊物质，其他电荷在电场中会受到电场力的作用。我们用电场线来可视化电场的分布。电场线从正电荷发出，终止于负电荷。电场线的密度表示电场强度的大小，线越密集的地方电场越强。电场线的方向表示正电荷在该点受力的方向。
静电在我们的日常生活中无处不在。常见的例子包括：用气球摩擦头发后气球能吸附头发丝；在干燥的天气里走过地毯再触摸金属时会被电击；从烘干机中取出衣物时衣物相互粘连；雷雨天的闪电也是大规模的静电现象。理解静电原理有助于我们解释这些日常现象，并学会如何防护和利用静电。