Energy of electric field of the condenser is, first of all, an energy of the most electric field. So that to understand what it depends on, it is necessary to understand how this type of energy is formed.
It is required to you
- The textbook in physics, the sheet of paper, a pencil
Instruction
1. Open the textbook in physics of the 10th class. You will find the subject "Electricity" in which it is possible to read the main definitions necessary for understanding of the studied subject in it. First, it is necessary to understand how electric field in the condenser is formed.
2. It is known that the condenser is the two plane-parallel plates having charges of the opposite sign. Actually, it is only one of subspecies of condensers, but its consideration is enough in this context. So, two plates of the condenser having different charges form in a gap among themselves electric field which energy needs to be measured.
3. Take the sheet of paper and represent the studied electric field in condenser facings. Draw two narrow vertical rectangles representing the condenser, and between them - the horizontal beams directed from a positively charged plate to negatively charged. Horizontal beams show the direction of a vector of strength of electric field of the condenser. Thus, the condenser saves in itself energy of this electric field. It is visible that if facings were the bigger size, then and the number of lines of tension would be more, so, there would be more also an energy of electric field. Thus, changing a condenser design, it is possible to affect energy of the electric field reserved in it. Actually, changing a condenser design, we, first of all, change its capacity.
4. Remember what determination of capacity of the condenser. The general determination of capacity says that it is equal to the relation of the charge reserved on one of condenser plates to tension received between plates. And capacity is the size of a constant and depending only on a condenser design.
5. Thus, at increase in a charge on facings also tension increases, and capacity remains to a constant. Using a concept of capacity and a charge of facings, it is possible to define energy of the field of the condenser as the charge square relation on one of plates to the doubled value of capacity of the condenser. It means that there are two ways to change energy of the condenser: changing capacity and changing a charge of plates. The first way is connected with change of the design of the condenser: it is possible to increase the area of plates or to reduce distance between plates. The second way is more obvious, it is quite natural that if to increase a charge of plates, then also the energy reserved in the condenser will increase.