It is difficult to imagine the electric device in which scheme there is no condenser which main characteristic is capacity. At designation of the condenser its nominal capacity is specified while actual capacity can change considerably.
Instruction
1. Capacity characterizesof ability of the conductor or the system of conductors to accumulate electric charge. This ability of the conductor is put in condensers into practice. The condenser call two conductors between which there is electric field which all power lines begin on one conductor and come to an end on another. On obk4ladkakh are equal in the simple condenser of size of charges in size, but are opposite according to the sign. The electric capacitance of the condenser is equal to the charge size relation on one of facings to potential difference in a general view between them: C = q/UZa unit of capacity is accepted 1 farad, that is the capacity of such condenser at which in the presence of a charge in 1 pendant the potential difference between facings is equal 1 volt. In a form of the carrying-out surfaces distinguish flat, cylindrical and spherical condensers.
2. Capacity of the flat condenser is calculated by a formula: C = εS/d, where ε – absolute dielectric permeability, S – the area of a plate of the conductor, d – distance between plates.
3. Capacity of the cylindrical condenser is calculated by a formula: C = 2πεl/ln (b/a) where l is length of the condenser, the radius of an external cylinder is b, an is the radius of an internal cylinder.
4. Capacity of the spherical condenser is calculated by a formula: C = 4πε / (1/a – 1/b), where a – the radius of the internal sphere, b – the radius of the external sphere.
5. Capacity of the two-wire line is calculated by a formula: With = πεl/ln(d/a) where l is length of wires, d – distance between axes of wires, a – their radius
6. For increase in capacity the condensers connect in batteries. In batteries of a facing of condensers connect in parallel, that is positively charged obkladkisoyedinyatsya in one group, negative in another. The electric capacitance of the battery of the condensers connected in parallel is equal to the sum of tanks of all condensers.C = to C1+C2+C3+ … +CnPri consecutive connection of condensers the loaded facings connect raznoimenno. The electric capacitance of the condensers connected consistently is equal to the return sum of their return containers.C = 1 / (1/C1+1/C2+1/C3+ … +1/Cn)