In DC circuit, capacitors are equivalent to circuit breakers. Capacitor is a component that can store charge, and it is also one of the most commonly used electronic components.
This has to be said from the structure of the capacitor. The simplest capacitor is made up of two ends of the polar plate and the middle insulating dielectric (including air). After electrification, the plate is electrified to form voltage (potential difference), but because of the insulating material in the middle, the whole capacitor is not conductive. However, such a situation is not precondition for exceeding the critical voltage of the capacitor (breakdown voltage). We know that any substance is relatively insulated. When the voltage at both ends of the material increases to a certain extent, the material can be conductive, which we call the breakdown voltage. The capacitor is no exception. If the capacitor is broken, it will not be an insulator. But in the middle school, such voltage is not seen in the circuit, so it works under breakdown voltage and can be regarded as insulator.
However, in AC circuits, the direction of current varies with time. The process of capacitor charging and discharging is time. At this time, a changing electric field is formed between the plates, and the electric field is also a function changing with time. In fact, current is passed through capacitors in the form of field.
In the middle school stage, there is a saying that it is called alternating current and DC blocking, which is the nature of capacitance.
Related reading: SMD Capacitor, Chip Capacitor
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