What is static electricity and what is its principle?
When an object has a certain amount of net positive or net negative charge, it can be said to carry static electricity. Static electricity is a relative term because in many cases, static electricity slowly decreases over time. The length of this period is related to the resistance of the object. Two extreme examples of practical applications are plastics and metals.
In general, plastics have very high electrical resistance, so plastics can remain static for long periods of time. The metal's resistance is very low, and the grounded metal has a very short period of static electricity. Static electricity is usually expressed in volts. Although the 220 volt AC power supply is dangerous, 100kV static electricity is very common. The voltage in an object is determined by two factors: the charge of the object and the capacitance of the object. It can be expressed in a simple relation, that is, Q=CV, where Q represents the amount of electricity, V represents the voltage, and C represents the capacitance of the object.
If the power of an object is given, the lower the capacitance, the higher the voltage and vice versa. Plastics generally have very low capacitance, so very little power can generate very high voltages. On the contrary, the capacitance of the metal is very high, so more electricity only produces a lower voltage. This is the reason why the problem of static electricity generated by using plastics is more important in practical applications. High voltages can attract dust, cause an operator to be shocked, or cause changes in object properties.
There are two main types of static electricity: body static and surface static. Body static refers to the charge distributed inside the object. Surface charge refers to the charge on the outermost surface of the object.
In practical applications, the problem of static electricity is basically related to surface static electricity. Although there is no way to neutralize static electricity, bulk statics rarely cause problems. Generally, the effect of body static is small compared to surface static.
What is the danger of static electricity to health?
Experts reminded that don't think that static electricity is just an uncomfortable thing, it has a negative impact on people's health. It has been confirmed by medical experts that skin electrostatic interference can change the normal potential difference of the human body surface and affect the normal electrophysiological process of the myocardium. This kind of static electricity can make the patient aggravate the condition. The long-lasting static electricity will also increase the alkalinity of the blood, causing itching and pigmentation of the skin, affecting the physiological balance of the human body and disturbing people's emotions.
Xiao Yu, an associate professor of dermatology at the Second Xiangya Hospital of Central South University, said that the incidence of facial diseases such as erythema and hyperpigmentation in white-collar workers in office computers is much higher than that of those who do not use computers. This is due to the static electricity generated by computer screens. A large amount of suspended dust causes the face to be stimulated.
Older people are more susceptible to static electricity because of the dryness of the skin of the elderly and the aging of the cardiovascular system and the weakening of the anti-interference ability of the elderly. The cardiovascular system originally has an elderly person with various lesions, and static electricity will make the condition worse. Excessive static electricity often causes anxiety, headache, chest tightness, difficulty breathing, and coughing.