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You will need

• Textbook on physics, sheet of paper, pencil

Instructions

1

Open the textbook on physics class 10. In it you will find the topic "Electricity", in which you can read the basic definitions necessary to understand the topic. First, it is necessary to understand how the electric field in the capacitor is formed.

2

As you know, the capacitor is twoplane-parallel plates having charges of the opposite sign. In fact, this is only one of the subspecies of capacitors, but its consideration is sufficient in this context. So, two capacitor plates having different charges form an electric field in the gap between themselves, the energy of which must be measured.

3

Take a sheet of paper and draw the subjectelectric field inside the capacitor plates. Draw two narrow vertical rectangles that represent the capacitor itself, and between them - horizontal rays directed from the positively charged plate to the negatively charged one. The horizontal rays show the direction of the vector of the electric field strength of the capacitor. Thus, the capacitor accumulates in itself the energy of a given electric field. It can be seen that if the plates were of a larger size, then the number of tension lines would be larger, which means that the energy of the electric field would also be greater. Thus, by changing the design of the capacitor, it is possible to influence the energy of the electric field stored in it. In fact, by changing the design of the capacitor, we, first of all, change its capacitance.

4

Recall what is the definition of capacitycapacitor. The general definition of capacitance states that it is equal to the ratio of the charge stored on one of the capacitor plates to the voltage obtained between the plates. Moreover, the capacitance is a constant value and depends only on the design of the capacitor.

5

Thus, with increasing charge on the platesThe voltage also increases, and the capacity remains constant. Using the concept of capacitance and charge plates, you can determine the energy of the capacitor field as the ratio of the square of the charge on one of the plates to twice the capacitor's capacitance. This means that there are two ways to change the energy of the capacitor: changing the capacitance and changing the charge of the plates. The first method involves changing the very design of the capacitor: you can increase the area of ​​the plates or reduce the distance between the plates. The second method is more obvious, because it is quite natural that if you increase the charge of the plates, the energy stored in the capacitor will also increase.

Tip 2: What is the charge of a capacitor

The capacitor is an element of an electrical circuit that allows the accumulation of electrical charges. Electric charges are, as a rule, electrons.

The process of charging a capacitor

The capacitor is capable of accumulating electricalenergy by the accumulation of charged particles on their plates. Thus, an electric field of a certain intensity appears inside the capacitor. Imagine a device of a classical capacitor containing two plane-parallel plates. An electrical potential is applied to each capacitor plate. The potentials of each capacitor plate have the opposite sign. In practice, such a case corresponds to the connection of the capacitor to the electrochemical cell. Charged particles located on the negative pole of the cell are flowing onto one of the plates of the capacitor. Thus, the other plate turns out to be charged with the opposite sign. This creates an electric field inside the capacitor device. The charging process continues until the voltage between the plates becomes equal to the voltage of the cell. As a rule, a dielectric substance is placed inside the capacitor, so that the total voltage between the capacitor plates is added from the external applied voltage and internal voltage formed by the polar particles of the dielectric material.

The charge of the capacitor

So, each of the capacitor plates takesa certain number of charged particles. Since the plates are a metallic substance, only electrons can be free carriers. Consequently, only one of the plates accumulates charged particles in the form of electrons, and the other forms their excess, creating a certain positive charge. Thus, the total charge of the capacitor can be defined as the total charge of all electrons of one of the plates. This value can be calculated by knowing the capacitance of the capacitor. In this case, the value of the capacitor charge will be equal to the product of the capacitance and the voltage between the plates. The capacitance of a capacitor is a constant value, depending only on its configuration, so the total capacitor charge will depend only on the voltage value. However, there is a way to increase the capacitor charge simultaneously in two ways, reducing the distance between the plates. In this way it is possible to achieve both an increase in capacitance of the capacitor and an increase in the voltage on it. That is why the distance between the plates is minimized when making it.